Evidence of surface superconductivity and multi-quanta vortex states in a weakly-pinned single crystal of Ca3Ir4Sn13

TL;DR

This study reveals surface superconductivity and multi-quanta vortex states in Ca3Ir4Sn13, demonstrated through anomalous magnetization behaviors and the absence of pinned Abrikosov vortices, indicating complex vortex phenomena in this weakly-pinned superconductor.

Contribution

It provides experimental evidence of surface superconductivity and multi-quanta vortex states in Ca3Ir4Sn13, highlighting novel vortex behaviors not previously observed in this material.

Findings

Oscillatory magnetization below Tc

Non-uniqueness in magnetization states

Evidence for multi-quanta vortex states

Abstract

We report here the observation of anomalous paramagnetic signal(s) in the isofield field-cooled cool-down magnetization scans (MFCC(T)) recorded for a single crystal of a low Tc superconductor Ca3Ir4Sn13. Novel features emanating from the MFCC(T) response include an oscillatory magnetization behaviour below Tc and a rich multiplicity (non-uniqueness) in magnetization ranging from diamagnetism to paramagnetism at a given H, T value. The metastability in MFCC(T) has been ascribed to non-unique coexistence of multi-quanta vortex states and single quantum (Abrikosov) vortices. Additionally, the isothermal M(H) scans recorded across a short window of temperature just below Tc show evidence for only the multi-quanta vortex states in the domain of surface superconductivity, with no fingerprint(s) of pinned Abrikosov lattice.