arXiv subjects

M. C. Bonsager

Publications and source records attributed to M. C. Bonsager.

3 recordsLinked to original sources

arXiv1999

Pauli-Limited Superconductivity in Small Grains

We report on an exploration of the mean-field phase diagram for Pauli-limited superconductivity in small metallic grains. Emphasis is placed on the crossover from the ultra-small grain limit where superconductivity disappears to the bulk thin-film limit as the single-particle level spacing in the grain decreases. We find that the maximum Zeeman coupling strength compatible with superconductivity increases with decreasing grain size, in spite of a monotonically decreasing condensation energy per unit volume.

cond-mat.supr-con↗

arXiv1997

Frictional Coulomb drag in strong magnetic fields

A treatment of frictional Coulomb drag between two 2-dimensional electron layers in a strong perpendicular magnetic field, within the independent electron picture, is presented. Assuming fully resolved Landau levels, the linear response theory expression for the transresistivity $ρ_{21}$ is evaluated using diagrammatic techniques. The transresistivity is given by an integral over energy and momentum transfer weighted by the product of the screened interlayer interaction and the phase-space for scattering events. We demonstrate, by a numerical analysis of the transresistivity, that for well-resolved Landau levels the interplay between these two factors leads to characteristic features in both the magnetic field- and the temperature dependence of $ρ_{21}$. Numerical results are compared with recent experiments.

cond-mat↗

arXiv1996

Magneto-Coulomb drag: interplay of electron--electron interactions and Landau quantization

We use the Kubo formalism to calculate the transresistivity $ρ_{21}$ for carriers in coupled quantum wells in a large perpendicular magnetic field $B$. We find that $ρ_{21}$ is enhanced by approximately 50--100 times over that of the B=0 case in the interplateau regions of the integer quantum Hall effect. The presence of both electron--electron interactions and Landau quantization results in (i) a twin-peaked structure of $ρ_{21}(B)$ in the inter-plateau regions at low temperatures, and, (ii) for the chemical potential at the center of a Landau level band, a peaked temperature dependence of $ρ_{21}(T)/T^2$.

cond-mat↗