Type-II Superconductivity below 4K in Sn0.4Sb0.6

TL;DR

This study reports the discovery of Type-II superconductivity below 4K in Sn0.4Sb0.6 single crystals, confirmed by various characterization techniques and critical field measurements.

Contribution

First demonstration of superconductivity in Sn0.4Sb0.6 with detailed structural, magnetic, and superconducting property analysis.

Findings

Superconductivity observed below 4K with sharp transition at 4K.

Type-II superconductivity confirmed by critical field and Ginzburg-Landau parameter.

Weak granular coupling indicated by resistance measurements.

Abstract

In this article, we report the occurrence of superconductivity in Sn0.4Sb0.6 single crystal at below 4K. Rietveld refined Powder XRD data confirms the phase purity of as grown crystal, crystallizing in rhombohedral R-3m space group with an elongated (2xc) unit cell in c-direction. Scanning Electron Microscope (SEM) image and EDAX measurement confirm the laminar growth and near to desired stoichiometry ratio. Raman Spectroscopy data shows the vibrational modes of Sn-Sb and Sb-Sb modes at 110 and 135cm-1. ZFC (Zero-Field-Cooled) magnetization measurements done at 10Oe showed sharp superconducting transitions at 4K along with a minor step at 3.5K. On the other hand, Paramagnetic Meissner Effect (PME) is observed in FC measurements. Magnetization vs applied field (M-H) plots at 2, 2.2, 2.5, 2.7, 3, 3.2, 3.5, and 3.7K shows typical Type-II nature of observed superconductivity with lower and upper critical fields (Hc1 and Hc2) at 69.42Oe and 630Oe respectively at 2K. Type-II superconductivity is also confirmed by calculated Ginzburg-Landau Kappa parameter value of 3.55. Characteristics length viz. coherence length and penetration depth are also calculated. Weak granular coupling is observed from R-T plot, in which resistance is not dropping to zero down to 2K.