Superconducting fluctuation induced conductance corrections near a pair-breaking quantum p

Superconducting fluctuation induced conductance corrections near a pair-breaking quantum phase transition in doubly connected ultrathin cylinders

of Al

Ke Zhang; ZongLi Wang; Da Xu; YaZhe Wang; H.Wang; Ying Liu

【期刊名称】《中国科学》 【年(卷),期】2020(063)003

【摘要】We report measurements on ultrathin,doubly connected superconducting cylinders of Al that exhibit a destructive regime,which refers to the loss of superconductivity in a doubly connected superconductor near applied half flux quanta due to the sample topology and the small size of the sample.A depairing quantum phase transition(QPT)between a superconducting and metallic state tuned by the magnetic flux enclosed in the quasi one-dimensional(1D)cylinder was found at the onset of the destructive regime.Results on magnetic flux and temperature dependent sample resistance as well as current-voltage characteristics revealed the presence of both thermally activated and quantum phase slips near the depairing QPT.On the superconducting side of the QPT,thermally activated phase slips as described

by

the

Langer-Ambegaokar

and

McCumber-

Halperin(LAMH)theory were found to describe the sample resistance as the system was pushed towards the QPT by a magnetic field applied