Sudhansu S. Mandal

Electrical conduction in lead - iron glasses

Temperature and compositional dependences of electrical conductivity in lead - iron glasses are reported. The experimental results are analysed in the light of existing theories. It has been observed that the electrical conduction in these glass compositions at high temperatures is best described by Motts phonon-assisted hopping model, while the low-temperature data are consistent with the variable-range hopping model. Hopping at high temperatures occurs in the non-adiabatic regime. The generalized hopping model of Schnakenberg is the best to interpret the temperature dependences of the conductivity and activation energy over the glass compositions studied. Values of the physical parameters obtained by the best fits of the experimental data are consistent with the glass compositions.

Effective actions and phase fluctuations in d -wave superconductors

We study effective actions for order-parameter fluctuations at low temperature in layered d-wave superconductors such as the cuprates. The order parameter lives on the bonds of a square lattice and has two amplitude and two phase modes associated with it. The low-frequency spectral weights for amplitude and relative phase fluctuations is determined and found to be subdominant to quasiparticle contributions. The Goldstone phase mode and its coupling to density fluctuations in charged systems is treated in a gauge-invariant manner. The Gaussian phase action is used to study both the c-axis Josephson plasmon and the more conventional in-plane plasmon in the cuprates. We go beyond the Gaussian theory by deriving a coarse-grained quantum

Theoretical search for the nested quantum Hall effect of composite fermions

\mathrm{XY}

Structural studies of binary iron vanadate glass

model, which incorporates important cutoff effects overlooked in previous studies. A variational analysis of this effective model shows that in the cuprates, quantum effects of phase fluctuations are important in reducing the zero-temperature superfluid stiffness, but thermal effects are small for

Glass formation in the PbO-Fe2O3 system with high PbO content

T\ensuremath{\ll}{T}_{c}.

How universal is the fractional-quantum-Hall edge Luttinger liquid?

Almost all quantum Hall effect to date can be understood as integral quantum Hall effect of appropriate particles, namely, electrons or composite fermions. This paper investigates theoretically the feasibility of nested states of composite fermions which would lead to a quantum Hall effect that cannot be understood as integral quantum Hall effect of composite fermions. The weak residual interaction between composite fermions will play a crucial role in the establishment of such quantum Hall states by opening a gap in a partially filled composite-fermion level. To treat the problem of interacting composite fermions, we develop a powerful method that allows us to obtain the low-energy spectra at composite-fermion fillings of

Two-dimensional electron system in high magnetic fields: Wigner crystal versus composite-fermion liquid.

{\ensuremath{\nu}}^{*}=n+\overline{\ensuremath{\nu}}

Relevance of inter-composite-fermion interaction to the edge Tomonaga-Luttinger liquid.

without making any assumption regarding the structure of composite fermions in the topmost partially filled level. The method is exact aside from neglecting the composite-fermion Landau level mixing, and enables us to study rather large systems, for example, 24 particles at a total flux of

Partially spin-polarized quantum Hall effect in the filling factor range 1/3<v<2/5

62hc/e,