Strong paramagnetic response in Y containing V$_{0.6}$Ti$_{0.4}$ superconductor

TL;DR

This study investigates the paramagnetic response in Y-containing V$_{0.6}$Ti$_{0.4}$ superconductors, revealing flux compression and high field paramagnetic Meissner effect due to Y-induced pinning variations.

Contribution

It demonstrates the link between Y addition, pinning strength differences, and the emergence of high field paramagnetic Meissner effect in this superconductor.

Findings

Paramagnetic response observed below T_c in low magnetic fields.

Y addition causes flux compression leading to paramagnetic effects.

Enhanced HFPME observed after cold work treatment.

Abstract

We report here, the systematic field-cooled (FC) magnetisation of superconducting (V$_{0.6}$Ti$_{0.4}$)-Y alloys in presence of applied magnetic fields upto 7 T. Paramagnetic response is clearly observed just below the superconducting transition temperature (T$_{c}$) in low fields ($\leq$0.2 T). The lower T$_{c}$ of the Y-rich precipitates as compared to the bulk, is the origin of flux compression and this leads to paramagnetic response. It is also observed that the magnetisation obtained during field cooled (FC) cooling cycle is lower than that of FC warming, for all the alloys in the field range 0.02-7 T. In addition, paramagnetic relaxation of FC moment is observed. We identify that these features of Y containing alloys are related to the high field paramagnetic Meissner effect (HFPME). Our analysis shows that the large difference in pinning strength of the different pinning centres generated due to Y addition to V$_{0.6}$Ti$_{0.4}$ alloy, is responsible for the observed effect. We provide further evidence to our claim in the form of extension of range in temperature and magnetic fields over which HFPME is observed when samples are subjected to cold work.