Anisotropy of superconducting single crystal SmFeAsO_(0.8)F_(0.2) studied by torque magnetometry

TL;DR

This study investigates the anisotropic magnetic properties of SmFeAsO_(0.8)F_(0.2) single crystals using torque magnetometry, revealing temperature-dependent anisotropy indicative of unconventional superconductivity.

Contribution

First measurement of anisotropic magnetic properties of SmFeAsO_(0.8)F_(0.2) single crystals using torque magnetometry, highlighting unusual temperature dependence of anisotropy.

Findings

Anisotropy parameter varies from 8 to 23 with temperature.

Anisotropy is field independent.

Unusual temperature dependence suggests unconventional superconductivity.

Abstract

Single crystals of the oxypnictide superconductor SmFeAsO_(0.8)F_(0.2) with T_c=45(1) K were investigated by torque magnetometry. The crystals of mass~0.1 mug were grown by a high-pressure cubic anvil technique. The use of a high-sensitive piezoresistive torque sensor made it possible to study the anisotropic magnetic properties of these tiny crystals. The anisotropy parameter was found to be field independent, but varies strongly with temperature ranging from 8 at T=T_c to 23 at T=0.4T_c. This unusual behavior signals unconventional superconductivity.