arXiv subjects

Yeshayahu Atzmon

Publications and source records attributed to Yeshayahu Atzmon.

3 recordsLinked to original sources

arXiv2013

Nernst Effect as a Signature of Quantum Fluctuations in Quasi-1D Superconductors

We study a model for the transverse thermoelectric response due to quantum superconducting fluctuations in a two-leg Josephson ladder, subject to a perpendicular magnetic field B and a transverse temperature gradient. The off-diagonal Peltier coefficient (α_{xy}) and the Nernst effect are evaluated as functions of B and the temperature T. The Nernst effect is found to exhibit a prominent peak close to the superconductor-insulator transition (SIT), which becomes progressively enhanced at low T. In addition, we derive a relation to diamagnetic response: α_{xy}= -M/T_0, where M is the equilibrium magnetization and T_0 a plasma energy in the superconducting legs.

cond-mat.supr-con↗

arXiv2011

Alternating Superconductor--Insulator Transport Characteristics in a Quantum Vortex Chain

Experimental studies of magnetoresistance in thin superconducting strips subject to a perpendicular magnetic field B exhibit a multitude of transitions, from superconductor to insulator and vice versa alternately. Motivated by this observation, we study a theoretical model for the transport properties of a ladder--like superconducting device close to a superconductor--insulator transition. In this regime, strong quantum fluctuations dominate the dynamics of the vortex chain forming along the device. Utilizing a mapping of the vortex system at low energies to one-dimensional (1D) Fermions at a chemical potential dictated by B, we find that a quantum phase transition of the Ising type occurs at critical values of the vortex filling, from a superconducting phase near integer filling to an insulator near 1/2-filling. The current--voltage (I-V) characteristics of the weakly disordered device in the presence of a d.c. current bias I is evaluated, and investigated as a function of B, I, the temperature T and the disorder strength. In the Ohmic regime (I/e << T), the resulting magnetoresistance R(B) exhibits oscillations similar to the experimental observation. More generally, we find that the I-V characteristics of the system manifests a dramatically distinct behavior in the superconducting and insulating regimes.

cond-mat.str-el↗

arXiv2011

Superconductor-Insulator Magneto-Oscillations in Superconducting Strips

The magnetoresistance of thin superconducting strips subject to a perpendicular magnetic field B and low temperatures T manifests a sequence of alternating superconductor-insulator transitions (SIT). We study this phenomenon within a quasi one-dimensional (1D) model for the quantum dynamics of vortices in a line-junction between coupled parallel SC wires, at parameters close to their SIT. Mapping the vortex system to 1D Fermions at a chemical potential dictated by B, we find that a quantum phase transition of the Ising type occurs at critical values of the vortex filling, from a SC phase near integer filling to an insulator near 1/2-filling. For T->0, the resulting magnetoresistance R(B) exhibits oscillations similar to the experimental observation.

cond-mat.supr-con↗