| 1 | Full name | Narendra KUMAR | |
| 2 |
Date
&
Place of birth |
1
February 1940
Bilaspur, Madhya Pradesh,
India |
|
| 3 | Present position |
Homi
Bhabha Distinguished Professor
Raman
Research Institute
Bangalore 560080, India |
|
| 4 | Academic |
B.Tech.
(Honours) - Electronics & Electrical Communication Engineering.
Indian
Institute of Technology (IIT),
Kharagpur
(1962) - I Class and II Rank
Prize
for best dissertation
M.Tech.
- Electronics & Electrical Commu-nication Engineering (Ultra High Frequency
and Microwave Engineering) -
IIT,
Kharagpur (1963) - I Class & I Rank.
I
Rank in All India Engg. (Electronics) Services Examination (1962).
Ph.
D. (Physics) - IIT, Bombay (1971)
|
|
| 5 | Field of Research and specialization | Condensed Matter Physics; Quantum and Classical Transport in Disordered Systems; Anderson-Mott Localization; Magnetism; High-Tc Superconductivity; Statistical Physics. | |
| Other areas | General Relativity; Astrophysics; Complex Systems: Associative Memory, Neural Net-work, turbulence, chaos. | ||
|
6 |
Scientific
Publications |
165 original publications in International Journals. See list attached. |
|
| 7 | Books Published |
Interactions
in Magnetically Ordered Solids K.P.Sinha and N.Kumar
(Oxford
Univ. Press, 1980)
Invitation
to Contemporary Physics
Quang
Ho-Kim, N.Kumar and C.S.Lam
(World
Scientific, 1991, Second Editiion, 2004)
Deterministic Chaos: Complex Chance out
of Simple
Necessity,
(Universities Press, 1996) Quantum Transport in
Mesoscopic Systems: Complexity and Statistical Flcutuations
|
|
| 8 | Professional Recognition |
Fellow,
Indian Academy of Sciences,
Bangalore
(1985)
Fellow, Indian National Science Academy, Delhi
(1987)
Fellow, The National Academy of Sciences, India
(1994)
Fellow, American Physical Society (1994) Associate & Senior Associate Member,
ICTP, Trieste (1970 - 1992)
Staff
Associate (1993 - )
|
|
| 9 | Awards and Distinctions |
Bhatnagar
Prize (1985) for Physical Sciences,
for
his contributions to the Physics of
Disordered
Systems.
Gold
Medal of the Sardar Patel University for
best
published papers (1985-86).
TWAS Award in Physics (1992) of the III
World Academy of Sciences, Trieste.
Distinguished Alumnus Award (1996) Indian
Institute of Technology, Bombay.
Jawaharlal Nehru Birth Centenary Lecture (1996),
Indian National Science Academy
Mysore Sales International Ltd. MSIL Chair (1990
- 1996) at IISc
Honorary Professor (1990 - ) Jawaharlal
Nehru Centre for Advanced
Scientific
Research
Visiting
Professor, Raman Research Institute,
Bangalore
(1991 - 1994)
Mahendra Lal Sircar Prize in Physics (1997) Goyal Award in Physics (1998) President, Indian Academy of Sciences (1998
- 2000)
FICCI Award for Physical Sciences for 1998-99 C.V. Raman Birth Centenary Award for 1999- 2000
Meghnad Saha Medal for 2000 |
|
|
10 |
Other positions held |
Director (1994 - 2005) Raman Research Institute Bangalore Professor (1975 -1994)
Assistant Professor (1971
- 75)
Scientist 'B' (1965 - 68)
Senior Scientific Officer
(SSO II) (1963 - 65)
|
|
|
11 |
Visiting positions |
Post-doctoral Teaching Fellow with Prof. M.H.L. University of British Columbia, Vancouver, Canada Visiting Professor (1975-76)
Visiting Professor (1978-79)
Visiting Professor (1984)
Visiting Professor (1985)
Visiting Scientist (1988
- 89)
Visiting Professor
|
|
Significant Research Contributions
In about 145 original papers published during 1970-2000 in international journals of repute, Prof. N. Kumar has made wide ranging and substantial contributions in the field of Condensed Matter Physics (theory), specially in the area of (I) classical and quantum transport in disorde5 June 2000red systems, (ii) phase transition, and (iii) superconductivity. In his early researches, he has also addressed problems of general relativistic evolutionary cosmology and of astrophysics (see refs. 13,14,15,27,29 in the list of publications). In the following, some of his major contributions are outlined.
1. Energy transport in glassy state. [Phys. Rev. Letters, 36, 1406 (1976)]. Resolved the anomalies of transient specific heat experiments by treating the crucial energy exchange between the fast and the slow degrees of freedom via coupled Boltzmann-Diffusion equation. This theory was adapted and refined by several workers, notably by J.L.Black at Harvard [Phys. Rev. B17, 2740 (1978)].
2. Quantum transport in dynamically disordered conductors. [Phys. Rev. Letters, 48, 553 (1982)]. The problem of electron transport in dynamically disordered lattices has been generally treated in terms of a parametric modulation of the lattice potential by the thermal phonon field. In an exact solution of the problem he pointed out that this neglects the effect of electron acting back on the lattice (back-action-evasion) and effectively ignores the dissipation concomitant with fluctuations. The exact results obtained by him provided a check on subsequent treatments by several workers, notably by W. Hänsch and G.D.Mahan [Phys. Rev. B28, 1902 (1992)].
3. Quantum resistance
fluctuations in disordered metals. By far his most significant contribution
in which he was among the first few to treat probabilistically the non-self
averaging nature of resistance near the mobility edge ([J. Phys. C19,
L85 (1986)]. He adapted the powerful invariant imbedding approach to treat
these resistance fluctuations exactly for a one-channel system [Phys.
Rev. B31, 5513 (1985)] and later generalized it to arbitrary
dimensions following the Kadanoff Migdal approximation. Later he and his
collaborators developed a novel approach based on Maximum Entropy Principle
to treat the N-channel case [Annals of Phys., 181, 290 (1988)]
that was eventually shown to give the universal conductance fluctuation
by
Pier Mello. Interest in
the general equation for the probability distribution of the transmission
matrix eigenvalues derived by us, now referred to as the DMPK (Dorokhov-Mello-Pereyra-Kumar)
equation by several workers in the field, has been revived recently by
its mapping to the well known Calogero-Sutherland model [see, e.g., M.
Caselle, Phys. Rev. Lett.74, 2776 (1995); Claus Frahm, Phys.
Rev. Lett. 74, 4706 (1995)].
4. Probabilistic formulations of phase transition. He proposed the novel idea of infinite divisibility of the singular part of the partition function at the critical point. [Lett. Nuovo Cimento, 11, 39 (1970)] anticipating thus the probabilistic approach to phase transition developed by Jona-Lasinio et al..
5. Normal state transport in high - Tc superconductors. [Phys. Rev. B45, 5001 (1992)]. He has proposed a subtle mechanism in which electrical transport along the c-axis of high Tc layered oxides is pictured as a coherent interplanar tunneling between neighboring layers blocked by repeated intraplanar incoherent scatterings. This gives the same temperature dependence for the c-axis resistivity as that for the in-plane resistivity. Additional temperature dependence can arise from the temperature-dependent renormalisation of the tunneling matrix element by an ohmic coupling to adiabatic phonons because of the large effective electron mass along the c-axis. This is consistent with recent experimental results on single crystals.
P.W.Anderson has recently referred to this to be as essentially correct and included it as such in Chapter VI of his recent book already in circulation as fascicular preprints.
6. Coherent multiple scattering of light in a highly scattering medium [Phys. Rev. Lett. 72, 2963 (1994)]. The polarization dependence of the intensity autocorrelation of light multiply scattered by dense crystallizing colloidal polyball suspension was studied experimentally, and analysed theoretically in terms of the anisotropic fluctuations of the medium. The study strongly suggests an imperfectly crystalline phase which remains (locally) soft orientationally but hard translationally.
7. Boson localization
in an amplifying random medium [Phys. Rev. B (Rapid Communications)
B48,
(1994)]. Proposes and analyses the possibility of mirror-less
lasing action in an amplifying
random optical medium in which Anderson localization provides the necessary
confinement.
His other important works include exact results in metallic adhesion [Phys. Rev., B9 (1975)], two-Boson mechanism of superconductivity [Phys. Rev. B9, 4993 (1970)] that V.L.Ginzburg classified as non-equilibrium mechanism), weak-localization [Phys. Rev. Letts. 59, 1953 (1987)], and more recently magnetic pairing in high-temperature superconductors [Phys. Rev. B42, 6138 (1990) and Phys. Rev. B40, 844 (1989)]. He coauthored a monograph on Interaction in magnetically ordered solids, K.P.Sinha and N.Kumar (Oxford University Press, 1980)], and a book Invitation to Contemporary Physics with Ho-Kim Quang and C.S.Lam (World Scientific, 1991).
In recognition of his scientific accomplishments, he was elected Fellow of the Indian Academy of Sciences (1983), Fellow of the Indian National Science Academy (1986), Associate (1970) and Senior Associate Member ICTP (1980), Honorary Professor at Jawaharlal Nehru Centre for Advanced Scientific Research (1990). In 1985 he was awarded the prestigious Bhatnagar Prize for Physics by the Council of Scientific and Industrial Research, India. He was given the 1992 TWAS Award in Physics by the third World Academy of Sciences.
His current interests include
high-temperature superconductivity, complex systems (neural networks and
associative memory, chaos and turbulence) and Astrophysics.
In the course of
his scientific career, he has collaborated with physicists from different
parts of the world notably with M H L Pryce,FRS (Canada), J Heinrichs (Belgium),
F Brouers (France), A M Jayannavar (India), J O Strom-Olsen (Canada), Pier
A Mello (Mexico), N H March (U K), K P Sinha (India), T V Ramakrishnan
(India), C N R Rao (India), Patrick A. Lee (USA) and Boris Shapiro (Israel).
Prof. N. Kumar is a Condensed
Matter Physicist with over 145 research publications, out of which 50 were
published in the last ten years in which he has made outstanding contributions
to the physics of disordered systems (25 papers) and superconductivity
(15 Publications). More specifically, the most important in these are:
a) Quantum Transport in Disordered Systems
(Annals
of Physics, 181, 290, (1988))
For quantum coherent transport
through disordered systems, the idea of an ensemble averaged material specific
transport coefficient (local resistivity/conductivity) must be replaced
by that of the global resistance/conductance which is specific to sample
and the probe (because of quantum interference effects). The latter is
best expressed in terms of the reflection/transmission coefficient for
the sample as a whole. This seminal work by him, done in collaboration
with Mello and Pereyra, is culmination of a series of earlier papers by
him in which the transport properties could be expressed in terms of the
general properties of the scattering matrix for the sample, under conditions
of unitarity, time-reversal symmetry and serial composition law for the
S-matrices. The equation thus derived for the size-dependence of the probability
distribution of the S-matrix, now well known as the DMPK (Dorokhov-Mello-Pereyra-Kumar)
Equation has become central to Mesoscopic Physics. Many of the 100+ citations,
at last count, not merely cite the paper but are essentially based on it
- indeed many have the DMPK Equation featuring in the title, or in the
Abstract itself. The equation has led to new and general understanding
of universality of conductance fluctuation and other statistical aspects
of random coherent transport. An extensive review of the DMPK equation
is contained in "C.W.J. Beenakker, Rev. Mod. Phys. 69, p.731
(1997)".
b) Normal-State c-axis Transport in High-Tc Superconductors
(Phys.
Rev. B45, 5001, (1992))
The temperature-dependence
of the normal-state c-axis resistivity of the layered high-Tc superconductors
is known to be anomalous, and possibly a key to understanding the high-Tc
superconductivity itself. It was shown that the c-axis resistivity arises
from the blocking of the coherent single particle inter-planar tunneling
by the strong intra-planar electron-electron scattering. Super-conductivity
can then result from the recovery of the inter-planar coherence possible
for pair-tunneling. This work with 50+ citations from leaders in this field
(including P.W.Anderson) has become central to the works of many other
researchers in this all important and highly competitive field. The idea
is robust and of far reaching consequences.
c) Random Amplifying Medium and Turbid Mirror-less Laser
(Phys.
Rev. B50, Rapid Communication, 9644, (1994))
In this pioneering work, he studied the synergy between the two coherent effects -- disorder-induced localization of light and coherent amplification of light by stimulated emission. Based on his earlier work on invariant-imbedding approach to resistance fluctuation (Phys. Rev. B31, 5513 (1985)), he established super-reflection from such a random-amplifying medium and derived its fluctuation statistics, suggesting thereby the possibility of Random Mirror-less lasers, where Anderson localization effectively provides the high-Q cavity. This work has motivated a flurry of activity in India and abroad, particularly by the Group of C.W.J. Beenakker (Phys. Rev. Lett. 76, 1368 (1996)) and of Z.Q. Zhang, Phys. Rev. B52, 7960 (1995). The work is receiving increasing world-wide attention. It was recently been commented upon by D.S. Wiersma in Physics World (January 1997).
At Raman Research Institute
this has led to interesting experimental-theoretical investigations (Applied
Optics, 36, p. 7718 (1997)) where they have observed the Random
lasing effect, surprisingly even in the sub-meanfree path samples of random
amplifying suspension.
d)
Novel Polarization Effects in Diffusing-wave Spectroscopy of Crystallising
Colloidal Suspension (Phys. Rev. Lett. 72, 2963 (1994)).
In this recent work, done
in collaboration with experimentalist colleagues at RRI and IISc, it was
shown how a polarized light can, despite being multiply scattered (in an
aqueous polyball suspension), show relative-polarization dependent de-correlation
times, assuming the polarization to be parallel transported. This work
resolves the puzzle and is now being pursued actively by several groups.
e) c-Axis Resistivity
and High-Tc Superconductivity (N. e) Kumar, T.P. Pareek and
A.M. Jayannavar
(Phys. Rev. B, 57, p.13399 (1998))
The recently proposed
mechanism for the normal-state c-axis resistivity of the high-Tc
layered cuprates that involved blocking of the single-particle tunneling
between the weakly coupled planes by strong intraplanar electron-electron
scattering is examined further for its implication for the ground-state
energy and superconductivity of the layered cuprates. It is now argued
that, unlike the single-particle tunneling, the tunneling of a boson-like
pair between the planes prepared in the BCS-type coherent trial state remains
unblocked
inasmuch as the latter is by construction an eigenstate of the pair-annihilation
operator. The resulting pair delocalization along the c axis offers
energetically a comparative advantage to the paired-up trial state, and
thus stabilizes superconductivity. In this scheme the strongly correlated
nature of the layered system enters only through the blocking effect,
namely, that a given electron is effectively repeatedly
monitored (intraplanarly
scattered) by the other electrons acting as an environment, on a time scale
shorter than the interplanar tunneling time. This work has opened up a
new direction in search for the mechanism of High-Tc Superconductivity.
List
of Publications of Prof. N. Kumar
1 A Prabhakar and N Kumar,
Infinite
array of 1 Ohm resistors, Electronic Engg. (November Issue) (1964)
783.
2 Premswarup and N Kumar, Microwave Faraday rotation in ferrite powders' Nature 204 (1964) 947.
3 N Kumar and K P Sinha, Temperature dependent exchange narrowing of linewidth in EPR of interacting donors in Ge and Si, Zeit. f. Physik, 197 (1966) 26.
4 N Kumar and K P Sinha, A generalized direct exchange interaction: Application to Heusler alloys, Ind. J. Phys., 15 (1966) 62.
5 N Kumar and K P Sinha, A new mechanism for magnon-phonon relaxation process in ferromagnetic insulators, Physica, 36 (1967) 655.
6 N Kumar and K P Sinha, Path integral approach to interacting electron-phonon system, Nuovo Cimento, 51B (1967) 547.
7 A W Joshi and N Kumar, Spin wave impurity states in antiferromagnets, Nuovo Cimento, 51B (1967) 315.
8 N Kumar and K P Sinha, Spin-phonon relaxation due to transverse optical phonons, Physica, 34 (1967) 387.
9 N Kumar and K P Sinha, On the origin of giant magnetic moments, Proc. Phys. Soc. (London), 92 (1967) 426.
10 N Kumar and K P Sinha, On the giant magnetic moments, Phys. Lett., 24A (1967) 161.
11 N Kumar and K P Sinha, A new mechanism of linewidth maxima in ferromagnetic resonance, J. Appl. Phys. 39 (1968) 1073.
12 N Kumar and K P Sinha, Possibility of photo-induced superconductivity, Phys. Rev. 174 (1968) 482.
13 N Kumar, Zero point energy and continuous creation of matter in an expanding universe, Progr. Theor. Phys., 41 (1969) 382.
14 N Kumar, Note on the role of zero-point energy in evolutionary cosmology, J. Phys., A2 (1969) 210.
15 N Kumar, A model of rotating neutron star (pulsar), Phys. Lett. 30A (1969) 199.
16 N Kumar, Attractive electron-electron interaction induced by dynamical Jahn-Teller effect involving degenerate impurity orbitals: A theory of the impurity enhancement of the superconductive transition temperature in dilute alloys, Phys. Rev. B2 (1970) 2500.
17 N Kumar, Quantum kinematics of Fermi - Dirac. Sea-plus-one-electron problem, Proc. Ind. Acad. Sci., 124A (1971) 79.
18 N Kumar and K P Sinha, Insulator metal transition, Proc. Ind. Acad. Sci. 123A (1971) 313.
19 N Kumar and K P Sinha, Quantum theoretic explanation of Schwarz-Hora effect, Proc. Ind. Acad. Sci. (1971) 91.
20 L Krishnasamy and N Kumar, Phonon mediated two magnon scattering from ferromagnetic insulators, Phys. Lett., 41A (1972) 445.
21 N Kumar and R. Sridhar, Exact energy eigenvalues for an attractive Coulomb potential with zero-radius hard core, Phys. Lett., 39A (1972) 389.
22 N Kumar and R. Nandini, Undamped Cooper pairs in a non-degenerate electron system, Phys. Lett., 38A (1972) 425.
23 G Baskaran and N Kumar, Exactly soluble one-dimensional anisotropic Heisenberg Hamiltonian and phase transitions, Proc. Nucl. Phys. And Solid State Phys. Symposium, Bangalore, 1973.
24 N Kumar, M Muthanna and K P Sinha, One-mass quantization of elementary particles, Proc. Ind. Acad.Sci. 125A (1972) 57.
25 L Krishnasamy and N Kumar, Brillouin scattering by phonons renormalized by two-magnon excitations in ferromagnetic dielectrics, Phys. Stat. Sol. (b) , 60 (1973) 539.
26 K B Athreya, R B Subramanian and N Kumar, On the problem of non-transport of electrons in disordered systems, Curr. Sci. 41 (1973) 867.
27 A R Prasanna and N Kumar, Spin-precession of a charged particle in a magnetic field including the effects of general relativity, Progr. Theoret. Phys. 49 (1973) 1553.
28 N Kumar and K B Athreya, Three-dimensional Ising fluid model, Pramana, 1 (1973) 98.
29 N Kumar and R Nandini, Magnetic field due to the self-gravity induced electric dipole polarization of rotating massive body, Phys. Rev. D7 (1973) 3586.
30 N Kumar and R Nandini, On a problem in random lattice statics, Progr. Theoret. Phys. 49 (1973) 1420.
31 A K N Reddy and N Kumar, A dipole assisted mechanism of ion transport across excitable cell membrane, Curr. Sci. 42 (1973) 337.
32 R Nandini and N Kumar, Resistance minimum in dilute magnetic alloys in the absence of impurity moments, Phys. Stat. Sol. (b) 63 (1974) 377.
33 R E Amritkar and N Kumar, A semiphenomenological theory of the two phase transitions in liquid He below 3 mK, Letters Nuovo Cimento 10 (1974) 81.
34 N Kumar and A A Kumar, Infinite divisibility and critical phenomena, Letters Nuovo Cimento 11 (1974) 39.
35 N Kumar, Intrinsic two-phonon exchange mechanism of superconductivity and enhancement of Tc , Phys. Rev. B9 (1974) 4993.
36 N Kumar and R R Subramanian, A probabilistic approach to the problem of electron localization in disordered systems and sharpness of the mobility edge, J. Phys. C7 (1974) 1817.
37 R E Amritkar and N Kumar, Anomalous low temperature specific heat of solid helium, DAE Symposium, Calcutta 18C (1975) 329.
38 N Kumar and S C Chhajlany, Internal excitations of charged self-gravitating matter, Letters Nuovo Cimento 12 (1975) 683.
39 S C Chhajlany and N Kumar, Reinterpretation of the reciprocity theory of elementary particles, Letters Nuovo Cimento 13 (1975) 364.
40 S C Chhajlany and N Kumar, Strong-gravity bound quark-antiquark pairs and meson mass spectrum, Letters Nuovo Cimento 13 (1975) 649.
41 J Heinrichs and N Kumar, Exact result for bimetallic interfaces, Phys. Rev. B12 (1975) 802.
42 J Heinrichs and N Kumar, Binding energy of Wannier excitons in polar crystals, Solid State Comm. 16 (1975) 1035.
43 F Brouers and N Kumar, On the theory of localization in disordered systems, Solid State Comm. 17 (1975) 1453.
44 N. Kumar, J Heinrichs and A Anil Kumar, Self-consistent theory of localization in weakly disordered systems, Solid State Comm. 17 (1975) 541.
45 J Heinrichs and N Kumar, Simple exact treatment of conductance in a random Bethe lattice, J. Phys. C8 (1975) 541.
46 J Heinrichs and N Kumar, Force between metallic films at small separation, Solid. State Comm. 18 (1976) 961.
47 F Brouers, N Kumar and C Litt, Local spin-susceptibility in disordered alloys II, J. de Physique (Paris) 37 (1976) 235.
48 J Heinrichs, A Anil Kumar and N Kumar, Low-field hopping conduction in granular metals, J. Phys. C9 (1976) 3249.
49 N Kumar and J Heinrichs, Stochastic treatment of ac hopping conduction in granular metals, J. Phys. C9 (1976) 2331.
50 J Heinrichs and N Kumar, Transient effects in low-temperature specific heat of amorphous dielectrics, Phys. Rev. Lett. 36 (1976) 1406.
51 J Heinrichs, A Anil Kumar and N Kumar, Diffusion of localized optical excitations and trap emission in Ruby, J. Phys. C10 (1977) 391.
52 N Kumar, J Heinrichs and P Shukla, Localization in disordered systems and statistical mechanics of zero-component classical field, Seventh International Conference on Amor-phous and Liquid Semiconductors, Edinburgh (1977).
53 N Kumar and J Heinrichs, Renormalization group theoretical approach to electron localization in disordered systems, Phys. Stat. Sol. (b) 85 (1978) 163.
54 R F Amritkar and N Kumar,
Coherence
factors in excitonic insulators, Solid State Comm. 20 (1978)
627.
55 V Krishnan and N Kumar, Upper mass-limit for neutron star stability against black-hole formation, Astrophysics and Space Science 57 (1978) 241.
56 N Kumar, On renormalization group theoretical approach to Anderson localization, Curr. Sci., 47 (1978) 143.
57 Deepak Dhar and N Kumar, An exactly soluble model of spin glasses, DAE Symposium 22C (1979) 449.
58 J Heinrichs and N Kumar, Spectral diffusion in random lattices, Phys. Rev. B20 (1979) 1377.
59 A M Jayannavar and N Kumar, Orbital diamagnetism of a charged Brownian particle, J. Phys. A: General and Mathematical Physics 14 (1981) 1399.
60 R E Amritkar, N Kumar and R Srinivasan, Non-observability of ESR in supercondutors, Solid State Comm. 38 (1981) 1095.
61 N Kumar and A M Jayannavar, A note on the effective medium theory of random resistive-reactive medium, J. Phys. C: Solid State 14 (1981) L785.
62 N Kumar and A M Jayannavar, Frequency and temperature dependent mobility of a charged carrier on randomly interrupted strand. Phys. Rev. B35 (1982) 4391.
63 A M Jayannavar and N Kumar, Non-diffusive quantum transport in a dynamically disordered medium, Phys. Rev. Lett. 48 (1982) 553.
64 N Kumar, Note on the one-parameter scaling theory of localization, J. Phys. C: Solid State 16 (1983) L109.
65 N Kumar, Is one-parameter scaling ansatzconsistent? J. Phys. C 16 (1983) L745.
66 N Kumar, Classical and quantum diffusion with dissipation, Lecture Notes in Physics (Springer-Verlag, 1983) V. 184.
67 R B Pandey, N Kumar and D Stauffers, Speculations on self-avoiding surfaces in fractals - a mean field treatment. J. Phys. A: Math. Ge. 17 (1984) L859-861.
68 J Heinrichs and N Kumar, Non-diffusive classical transport in a medium with static randomness, J. Phys. C: Solid State 17 (1984) 769-774.
69 M E Farrell, M F Bishop, N Kumar and W E Lawrence, Localization effects in thin potassium wires, Extended Abstract in LITPTM International Conference on Localization, Interaction and Transport Phenomena in Impure Metals, Brauchweig, FRG, August 1984.
70 N Kumar, Invariant imbedding approach to the length-scale dependent conductance of a one-dimensional disordered medium, Curr. Sci. 53 (1984) 358.
71 J Heinrichs and N Kumar, Note on the physical interpretation of classical motion induced by static randomness, J. Phys. C. 17 (1984) L741.
72 N Kumar, Resistance fluctuation in a one-dimensional conductor with static disorder, Phys. Rev. B31 (1985) 5513.
73 S Arumugam, S V Bhat, N Kumar, K V Ramanathan and R Srinivasan, NMRand X-ray investigations of a plastic crystalline phase in MBBA, Mol.Cryst.Liq.Cryst. 104 (1984) 39.
74 N. Kumar, Quantum first-passage problem, Pramana - J. Phys., 25 (1985) 363.
75 N Kumar and P A Mello, Information theory and resistance fluctuation in 1-D disordered conductors, Phys. Rev. B31 (1985) 3109.
76 N Kumar and A M Jayannavar, Quantum diffusion in thin disordered wires, Phys. Rev. (Rapid Communications) B32 (1985) 3345.
77 Mary Eileen Farrell, Marilyn F Bishop, N Kumar and W E Lawrence, Localization effects in thin potassium wires, Phys. Rev. Lett. 55 (1985) 626.
78 N Kumar and A M Jayannavar, Resistance fluctuation at the mobility edge, J. Phys. C 19 (1986) L85.
79 N Kumar, Statistics of quantum fluctuation of resistance in a one-dimensional disordered conductor, Hadronic Journal, Suppl. 1 (1985) 610.
80 Pier A Mello and N Kumar, Information theory and one-dimensionaldisordered conductors, J. Non-Cryst. Solids 75 (1985) 135.
81 N Kumar, Quantum ohmic resistance fluctuation in disordered conductors - An invariant imbedding approach, Pramana 27 (1986) 33.
82 N Kumar, Quantum hall effect, Proc. National Symp. on Recent Developments in Theoretical Physics, Kottayam, Sept. 1986 - World Scientific Inc.
83 N Kumar, Quantum Ohm's law: Resistance fluctuation in disordered conductors, Proceedings of the Second Asia Pacific Physics Conference, Bangalore, 1986, Vol. II, Ed. S. Chandrasekhar (World Scientific, Singapore, 1987).
84 G V Vijayagovindan, A M Jayannavar and N Kumar, Electric-field dependent average resistance and the resistance fluctuation in one-dimensional disordered systems, Phys. Rev. B35 (1987) 2029.
85 P A Mello, P Pereyra and N Kumar, A soluble random-matrix model for relaxation in quantum systems, J. Stat. Phys. 51 (1988) 77
86 P A Mello, P Pereyra and N Kumar, A macroscopic approach to resistance fluctuation in disordered wires, Annals of Phys. 181 (1988) 290.
87 M M Mohan and N Kumar, Spin singlet d-wave hole pairing in the new high-Tc superconductors, J Phys. 20 (1987) C: L527.
88 N Kumar, David V Baxter, R Richter and J O Strom-Olsen, Weak localization in two and three dimensions: Dephasing by zero-point motion, Phys. Rev. Lett. 59 (1987) 1853.
89 A M Jayannavar and N Kumar, Mooij correlation in disordered metals, Phys. Rev. B37 (1988) 573.
90 N Kumar, David V Baxter, R Richter and J O Strom-Olsen, Weak localization in two and three dimensions: Dephasing by zero-point motion, Phys. Rev. Lett. 60 (1988) 1987.
91 N Kumar, Berry's phase and weak localization in the presence of spin-orbit interaction, Current Science, 57 (1988) 761.
92 N Kumar, Phenomenology and theory of superconductivity, ICTP (Trieste) Lecture Notes SMR/384- (1-7): Experimental Workshop on High Temperature Superconductivity, March- April 1989. Also, SMR/348-1 (April 1988).
93 N Kumar, A macroscopic approach to conductance fluctuation and universal conductance fluctuation: N-Channel case, ICTP (Trieste) Lecture Notes SNR/355-41 (1988). Also SMR/355-38 (1988).
94 R Simon and N Kumar, A note on the Berry phase for systems having one degree of freedom, J. Phys. A: Math. Gen. 21 (1988) 1725.
95 N Kumar, Hole pairing in Antiferro-magnetically correlated background, Proc. Interlaken Conf. on Superconductivity, 1988 - Physica C 153 (1988) 1227.
96 G V Vijayagovindan, A M Jayannavar and N Kumar, Energy dispersive back-scattering from a disordered medium and l/f noise, Z. Phys. B. Condensed Matter 75 (1989) 77.
97 N Kumar, Superconductivity: Introduction to Ginzburg-Landau phenomenology and micro-scopic BCS theory, BCSPIN Kathmandu School, May-June 1989, (World Scientific, Singapore).
98 S C Chhajlany, V N Mal'nev and N Kumar, Coulomb-diamagnetic problem in two dimensions, Phys. Rev. A 39 (1989).
99 A S G Rojo, N Kumar and C A Balseiro, Oscillatory magneto conductance of quantum double-well channels, Solid State Comm. 70 (1989) 485.
100 N Kumar, Temperature dependence of hole mobility in Mott insulators: Normal-state resistivity of high Tcsuperconductors, Phys. Rev. B40 (1989) 844.
101 C N R Rao, T V Ramakrishnan and N Kumar, Systematics in the thermopower behaviour of several series of Bismuth and Thallium Cuprate Superconductors: An interpretation, Physica C165 (1990) 183.
102 N Kumar, B Shapiro and P A Lee, Conduction in highly anisotropic metals, Proceedings of III BAR-ILAN Conference on Frontiers in Condensed Matter Physics, January 1990 - Physica A 168 (1990) 447.
103 N Kumar, Localization of isolated holes in a Mott insulator and delocalization by pairing, Phys. Rev. B42 (1990) 6138.
104 A M Jayannavar and N Kumar, Generalization of Bruggeman's unsymmetrical effective medium theory to a three-component composite, Phys. Rev. B44 (1991) 12014.
105 S V Bhat, V V Srinivasu and N Kumar, Temperature dependent phase reversal of non-resonant microwave and rf absorption in high-Tc superconductors, Phys. Rev. B44 (1991) 10121.
106 N Kumar and A M Jayannavar, Temperature dependence of c-axis resistivity of high-Tc layered oxides, Phys. Rev. B45 (1992) 5001.
107 N Kumar, One-parameter scaling: some open questions, in Ordering Disorder: Prospect and Retrospect in Condensed Matter Physics, Eds. V.Srivastava, A.K.Bhatnagar, D.G.Naugle, Proceedings of the Indo-US Workshop, Hyderabad, India 1992-93 (AIP Publication, New York, 1994), p.3.
108 A K Sood, N. Chandrabhas, D Victor S Muthu, A Jayaraman, N Kumar, H R Krishnamurthy, T Pradeep and C N R Rao, Pressure-induced shift of the photoluminescence band in single crystals on Buckminster Fullerene C60 and its implications for superconductivity in doped samples, Solid State Comm. 81 (1992) 89.
109 N Kumar, Looking through the ground glass, J. Indian Inst. Sci. 73 (1993) 171.
110 Nacir Tit, N Kumar, J W Halley and H Shore, Possibility of two types of localized states in a two-dimensional disordered lattice, Phys. Rev. B (Rapid Commns.) 47 (1993) 15988.
111 A Rubio and N Kumar, Reflection effect of localized absorptive potential on non-resonant and resonant tunneling, Phys. Rev. B47 (1993) 2420.
112 P Prabhakar and N Kumar, Suppression of conductance fluctuations in a 1D disordered system, Phys. Rev. B48 (1993) 5661.
113 N Kumar, Two-Fermi-liquid model for high-Tcsuperconductivity involving suppression of tunneling by decoherence, Curr. Sci. 64 (1993) 754.
114 M S Hegde, Bobin Thomas, N Y Vasanthacharya, S V Bhat, V V Srinivasu and N Kumar, Critical current variation with Prcontent in Y1-xPrx Ba2 ,Cu307epitaxial films, Phys. Rev. B48 (1993) 6465.
115 Nacir Tit, Prabhakar Pradhan and N Kumar, Length-scale-dependent ensemble averaged conductance of a 1D disordered conductor: Conductance minimum, Phys. Rev. B49 (1994) 14715.
116 S V Bhat, A Rastogi, N Kumar, R Nagarajan and C N R Rao, Paramagnetic Meissner effect in YBa2Cu3O7-8: A non-resonant microwave absorption study, Physica C: Superconductivity, C219 (1994) 87.
117 S Sanyal, A K Sood, S Ramkumar, S Ramaswamy and N Kumar, Novel polarization dependence in diffusing-wave spectroscopy of crystallizing colloidal suspensions, Phys. Rev. Lett. 72 (1994) 2963.
118 Prabhakar Pradhan and N Kumar, Localization of light in coherently amplifying random media, Phys. Rev. (Rapid Communications) B50 (1994) 9644.
119 N Kumar, A calculable quantum capacitance, Current Science 68 (1995) 945.
120 N Kumar and A M Jayannavar, Quantum diffusion and decoherence, in 'The Metal - Non-Metal Transition Revisited: A Tribute to Sir Nevill Mott', Ed. P.P.Edwards and C.N.R.Rao (Taylor & Francis, London, 1995) p.309.
121 N Kumar and A M Jayannavar, On minimum metallic diffusivity in disordered conductors, Current Science 69 (1995) 57.
122 N Kumar, Bose-Einstein condensation in a dilute atomic vapour , Current Science, 69 (1995) 492.
123 V Ashvin, G V Vijayagovindan and N Kumar, Tunneling conductance of Luttinger liquids: Resonances, Phys. Rev. B (Rapid Communications) 53 (1996)R13 239
124 Mulugeta Bekele, G Ananthakrishna and N Kumar, Optimal barrier subdivision for Kramers' escape rate, Pramana, 46 (1996) 403.
125 N Kumar and C N R Rao, The nature of charge ordering in rare earth manganates and its strong dependence on the size of the A-site cations, J. Solid State Chem. 129 (1997) 363.
126 N Kumar and A M Jayannavar, Statistics of mesoscopic fluctuations of quantum capacitance, Mod. Phys. Lett. B11 (1997) 53.
127 N Kumar, Hall angle in high-Tc cuprates: Anomalous temperature dependence and anisotropic scattering, Current Science, 73 (1997) 64.
128 N Kumar, T P Pareek and A M Jayannavar, Normal-state c-axis resistivity of the high-Tc cuprate superconductors, Modern Phys. Lett., B11 (1997) 347.
129 B Raghavendra Prasad, Hema Ramachandran, A K Sood, C K Subramanian and N Kumar, Lasing in active sub-meanfree path sized systems with dense random weak scatterers, Applied Optics, 36 (1997) 7718.
130 N Kumar E S Raja Gopal, One hundred years of the electron, IETE Technical Review, 14 (1997) 231.
131 N Kumar, G V Vijayagovindan and Prabhakar Pradhan, Spin-valve effect in Manganese-oxide perovskites: CMR, in Giant Magnetoresistance and related properties of metal oxides, edited by C.N.R. Rao and B. Raveau (World Scientific Publishing, Singapore 1998), pp.305- 324.
132 N Kumar, T P Pareek and A M Jayannavar, c-Axis resistivity and high-Tc superconductivity, Phys. Rev., B57 (1998) 13399.
133 N Kumar, Highly anisotropic layered systems: Intra-planar metallicity and inter-planar non-metallicity, Proceedings of the Ciba Foundation/Royal Society Discussion Meeting on "Metal-Non-Metal Transitions in Reduced Dimensions", March 1997, Eds. P.P.Edwards, R.L.Johnston, C.N.R.Rao and D.P.Tunstall - Philosophical Transactions of the Royal Society, London, 356 (1998) 261.
134 N Kumar, Prabhakar Pradhan and A M Jayannavar, Coherently amplifying random medium: Statistics of super-reflection, Special Issue on the Rolf Landauer's 70th Birthday, Superlattice and Microstructures 23 (1998) 853.
135 A Arulraj, P N Santhosh, R S Gopalan, A Guha, A K Raychaudhuri, N Kumar and C N R Rao, Charge-ordering in the rare earth manganates: Origin of the extraordinary sensitivity to the average radius of the A-site cations, <rA>, J. Phys. Condens. Matter, 10 (1998) 8497.
136 Prabhakar Pradhan and N Kumar, Geometric phase for a dimerized disordered continuum: Topological shot noise , Europhys. Lett., 44 (1998) 131.
137 N Kumar, Coherent wave transport in low dimensional random media, in Proceedings of the Tenth Summer School on Physics of Novel Materials, Australian National University, Canberra, January 1997 (World Scientific Publishing, Singapore, 1999), pp.315-381
138 Mulugeta Bekele, S Rajesh, G Ananthakrishna and N Kumar, Effect of blow-torch on Kramers escape rate, Phys. Rev., E59 (1999) 143.
139 N Kumar, Life before mean free path, Current Science, 76 (1999) 1330.
140 S Anantha Ramakrishna and N Kumar, Diffusion of particles moving with constant speed, Phys. Rev., E60 (1999) 1381.
141 T P Pareek, A M Jayannavar and N Kumar, Blocking of inter-subspace tunneling by intra sub-space inelastic scattering, Indian Journal of Physics, 23 (1998) 853
142 C N R Rao, A R Raju, V Ponnambalam, S Parashar and N Kumar, Electric-field induced melting of the randomly pinned charge-ordered states of rare earth manganates and associated effects, Phys. Rev., B61 (2000) 594.
143 S Anantha Ramakrishna and N Kumar, Imaginary potential as a counter of delay time for wave reflection from a one-dimensional random potential, Phys. Rev., B61 (2000) 3164.
144 S Anantha Ramakrishna, E Krishna Das, G V Vijayagovindan and N Kumar, Super-reflection of light from random amplifying medium with disorder in the complex reflractive index:Statistics of fluctuations, Phys. Rev., B62 (2000) 256.
145 N Kumar, Random amplifying medium: Statistics of super-reflectance and time-delay fluctuations, Physica E, 9 (2001) 356.
146 Venkatesh Gopal, S Anantha Ramakrishna, A K Sood and N Kumar, Photon transport in thin disordered slabs, Pramana, 56 (2001) 767.
147 N Kumar, The Zeno effect and an inter-layer pairing mechanism for high-temperature superconductivity in layered materials, Proceedings of the Eighth Asia-Pacific Physics Conference, eds. Yeong-Der Yao, Hai-Yang Cheng, Chia-Seng Chang and Shang-Fan Lee (World Scientific Publishing Co., 2001), p. 24.
148 M A H Ahsan and N. Kumar, Rotating Bose gas with hard-core repulsion in a quansi-2D harmonic trap: Vortices in BEC, Phys. Rev. A, 64 (2001) 13608.
149 S Dattagupta, A M Jayannavar and N Kumar, Landau diamagnetism revisited, Curr. Sci., 8 (2001) 863.
150 S A Ramakrishna and N Kumar, Distribution of the delay time and the dwell time for wave reflection from a long random potential, The European Physical Journal B, Section Mesoscopic Physics, 23 (2001) 515.
151 M Sanjay Kumar, S Dattagupta and N Kumar, Zeno blocking of interplanar tunneling by intraplanar inelastic scattering in oxide superconductors - a generalized spin-Boson analysis, Phys. Rev. B 65 (2002) 134501-1.
152 S Anantha Ramakrishna and N Kumar, Diffusion with constant speed in a model phase space, J. Mod. Phys., B 65 (2002) 3715.
153 Shankar Ghosh, A K Sood and N Kumar, Carbon nanotube flow sensors, Science, 299 (2003) 1042.
154 S Anantha Ramakrishna and N Kumar, Correcting the quantum clock: Conditinal sojourn times, Europhys. Lett., 60 (2002) 491.
155 N Kumar and C N R Rao, Stripes and superconductivity in cuprates - Is there a connection? Chemphyschem, 4, 439 (2003).
156 N Kumar, Normal-state c-axis resistivity of layered cuprates: Quantum Zeno effect, Proceedings of the XXVI Workshop on Condensed Matter Theories, Luso, Portugal, September 2002, Condensed Matter Theories, vol. 18, M. de Llano, C. Fiolhais and J. da Providencia, (editors), Nova Science Publishers, Inc., N.Y., 2004).
158 N Kumar, Left-handed medium is just right, in New Materials, Proceedings of Asia Academic Seminar, eds. P. Rama Rao, M. Doyama, G. Sundararajan, Y.R. Mahajan and K. Oda (International Advanced Research Centre for Powder Metallurgy & New Materials (ARCI) and Japan Society for Promotion of Science (JSPS), 2003), pp.33-39.
159 T Roopa, N Kumar, S Bhattacharya and G V Shivashankar, Dynamics of membrane nanotubulation and DNA self-assembly, Biophys. J. 87, 974 (2004).
160 S Ghosh, A K Sood, S R Ramaswamy and N Kumar, Flow-induced voltage and current generation in carbon nanotubes, Phys. Rev. B., 70 (2004) 205423.
161 A K Sood, S Ghosh and N Kumar, Flow driven electronic transport in carbon nanotube, International Journal of Nanoscience
162 N Kumar, "Viscosity of suspensions and the glass: Turning power-law divergence into essential singularity", Curr. Sci. 88, 143 (2005)
163 Navinder Singh and N Kumar, Dissipative electron-phonon photoexcited far from equilibrium, J. Stat. Mech. (2005)
164 N Kumar, Bosonic stimulation and the irreproducibility of condensate fragmentation, (e-print: cond-mat/0204443)
165 N Kumar, "Decohering quantum statistics: Suppression of BEC", Europhys. Lett. (cond- mat/0408007/31.7.2004).