arXiv subjects

Edouard B. Sonin

Publications and source records attributed to Edouard B. Sonin.

5 recordsLinked to original sources

arXiv2026

The theory of planar ballistic SNS junctions at $T=0$

The Letter presents the theory of planar ballistic SNS junctions at $T=0$ for any normal layer thickness $L$ taking into account phase gradients in superconducting leads. The current-phase relation was derived in the model of the steplike pairing potential analytically and is exact in the limit of large ratio of the Fermi energy to the superconducting gap. At small $L$ (short junction) the obtained current-phase relation is essentially different from that in the previous theory neglecting phase gradients. It was confirmed by recent numerical calculations and was observed in the experiment on short InAs nanowire Josephson junctions. The analysis resolves the problem with the charge conservation law in the steplike pairing potential model.

cond-mat.supr-con↗

arXiv2023

Reply to Comment on "Ballistic SNS sandwich as a Josephson junction"

This is the Reply to the Comment by E. Thuneberg refuting the paper by E. B.Sonin [Phys. Rev. B 104, 094517 (2021)] as incorrect. The criticism is based on a misunderstanding of the goal and the approach of the paper and does not provide any reasonable argument that it is incorrect.

cond-mat.supr-con↗

arXiv2022

Quantum rotator and Josephson junction: compact vs. extended phase and dissipative quantum phase transition

The paper reassesses the old dilemma "compact vs. extended phase" in the quantum theory of the rotator and the Josephson junction and the analogy of these two systems with the a particle moving in a periodic potential. This dilemma is in fact the dilemma whether the states with the phases $φ$ and $φ+2π$ are distinguishable, or not. In the past it was widely accepted that in the Josephson junction these states are distinguishable like for a particle moving in a periodic potential. This paper argues that the states with the phases $φ$ and $φ+2π$ are indistinguishable as in a pendulum (a particular example of the quantum rotator). However, this does not lead to revision of the conclusions of the conventional theory predicting the transition from the superconducting to the insulating state in the small Josephson junction.

cond-mat.other↗

arXiv2021

Ballistic SNS sandwich as a Josephson junction

The paper develops the theory of the ballistic SNS sandwich, in which the Josephson effect exists without the proximity effect. The theory takes into account restrictions imposed by the charge conservation law and the incommensurability of the superconducting gap with the Andreev level energy spacing. This resulted in revisions of some conclusions of previous works. In the one-dimensional case the Josephson phase of the ground state of the ballistic SNS sandwich is not necessarily zero but may have any value from 0 to $π$. If this value is $π$ this is a $π$ junction, which was well known before. The suppression of the supercurrent at temperatures on the order or higher than the Andreev level energy spacing, which was predicted in previous investigations, does not take place in the one-dimensional case. At zero temperature the ballistic SNS sandwich of any dimensionality is not a weak link. This leads to unusual properties: the absence of the Josephson plasma mode localized at the normal layer and the Meisner effect with the same London penetration depth in the normal and the superconducting layers.

cond-mat.supr-con↗

arXiv2003

The internal magnetic field in superconducting ferromagnets

We have measured the nonlinear response to the ac magnetic field in the superconducting weak ferromagnet Ru-1222, at different regimes of sample cooling which provides unambiguous evidence of the interplay of the domain structure and the vorticity in the superconducting state. This is {\em direct} proof of coexistence of ferromagnetic and superconductive order parameters in high-$T_c$ ruthenocuprates.

cond-mat.supr-con↗