Possible observation of phase separation near a quantum phase transition in doubly connected ultrathin superconducting cylinders of aluminum

TL;DR

This study investigates phase separation phenomena near a quantum phase transition in ultrathin aluminum superconducting cylinders, revealing resistance features suggestive of normal region nucleation during the transition.

Contribution

It provides evidence for phase separation near a quantum phase transition in ultrathin superconducting cylinders, a novel observation in this context.

Findings

Step-like resistance features near QPT

Normal regions nucleate within superconducting cylinders

Evidence suggests phase separation occurs near the QPT

Abstract

The kinetic energy of superconducting electrons in an ultrathin, doubly connected superconducting cylinder, determined by the applied flux, increases as the cylinder diameter decreases, leading to a destructive regime around half-flux quanta and a superconductor to normal metal quantum phase transition (QPT). Regular step-like features in resistance vs. temperature curves taken at fixed flux values were observed near the QPT in ultrathin Al cylinders. It is proposed that these features are most likely resulted from a phase separation near the QPT in which normal regions nucleate in a homogeneous superconducting cylinder.