Magnetization Relaxation and Collective Vortex Pinning in the Fe-Based Superconductor SmFeAsO_0.9F_0.1

TL;DR

This study investigates vortex dynamics in the Fe-based superconductor SmFeAsO_0.9F_0.1, revealing large relaxation rates, weak temperature dependence, and supporting the applicability of collective vortex pinning models.

Contribution

It provides the first detailed analysis of vortex relaxation and pinning mechanisms in SmFeAsO_0.9F_0.1, establishing the relevance of collective vortex pinning in this material.

Findings

Large relaxation rate indicating small pinning energy

Weak temperature dependence of relaxation rate

Vortex phase diagram consistent with collective pinning model

Abstract

By measuring the dynamic and traditional magnetization relaxations we investigate the vortex dynamics of the newly discovered superconductor SmFeAsO_0.9F_0.1 with Tc = 55K. It is found that the relaxation rate is rather large reflecting a small characteristic pinning energy. Moreover it shows a weak temperature dependence in wide temperature region, which resembles the behavior of the cuprate superconductors. Combining with the resistive data under different magnetic fields, a vortex phase diagram is obtained. Our results strongly suggest that the model of collective vortex pinning applies to this new superconductor very well.