Phase-sensitive quantum effects in Andreev conductance of the SNS system of metals with macroscopic phase breaking length

TL;DR

This study investigates phase-sensitive quantum interference effects in the conductance of a SNS interferometer with indium and aluminium, revealing oscillations related to coherence length and Josephson current contributions.

Contribution

It provides new insights into phase-sensitive quantum effects in SNS systems with macroscopic phase coherence, including the observation of resonance oscillations and their phase shifts.

Findings

Phase-sensitive conductance oscillations observed in SNS interferometer.

Resonance oscillations with phase shift of π identified.

Oscillation periods linked to coherence length and interferometer area.

Abstract

The dissipative component of electron transport through the doubly connected SNS Andreev interferometer indium (S)-aluminium (N)-indium (S) has been studied. Within helium temperature range, the conductance of the individual sections of the interferometer exhibits phase-sensitive oscillations of quantum-interference nature. In the non-domain (normal) state of indium narrowing adjacent to NS interface, the nonresonance oscillations have been observed, with the period inversely proportional to the area of the interferometer orifice. In the domain intermediate state of the narrowing, the magneto-temperature resistive oscillations appeared, with the period determined by the coherence length in the magnetic field equal to the critical one. The oscillating component of resonance form has been observed in the conductance of the macroscopic N-aluminium part of the system. The phase of the oscillations appears to be shifted by $\pi$ compared to that of nonresonance oscillations. We offer an explanation in terms of the contribution into Josephson current from the coherent quasiparticles with energies of order of the Thouless energy. The behavior of dissipative transport with temperature has been studied in a clean normal metal in the vicinity of a single point NS contact.