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

Abstract

a b s t r a c tWe report here the observation of anomalous paramagnetic signal(s) in the isofield field-cooled cooldown magnetization scans (M FCC ðTÞ) recorded for a single crystal of a low T c superconductor Ca 3 Ir 4 Sn 13 . Novel features emanating from the M FCC ðTÞ response include an oscillatory magnetization behavior below T c and a rich multiplicity (non-uniqueness) in magnetization ranging from diamagnetism to paramagnetism at a given H; T value. The metastability in M FCC ðTÞ has been ascribed to non-unique coexistence of multi-quanta vortex states (LU 0 ; U 0 ¼ hc=2e, L > 1) and single quantum (L ¼ 1, Abrikosov) vortices.Additionally, the isothermal MðHÞ scans recorded across a short window of temperature just below T c show evidence for only the multi-quanta vortex states in the domain of surface superconductivity, with no fingerprint(s) of pinned Abrikosov lattice.