Anisotropic Superconductivity of Ca1-xLaxFeAs2 (x ~ 0.18) Single Crystal

TL;DR

This study systematically investigates the anisotropic superconducting properties of Ca1-xLaxFeAs2 single crystals, revealing moderate anisotropy in critical fields, similar activation energies to NdFeAsO1-xFx, and high critical current densities indicating strong pinning.

Contribution

It provides the first comprehensive analysis of anisotropic superconductivity in Ca1-xLaxFeAs2 single crystals, highlighting their critical field anisotropy, activation energy, and current density characteristics.

Findings

Moderate anisotropy gamma of 2-4.2 in Hc2

Activation energy U0 similar to NdFeAsO1-xFx

Critical current density exceeding 10^5 A/cm2

Abstract

Anisotropic superconducting properties including the upper critical field Hc2, thermal activation energy U0, and critical current density Jc are systematically studied in a large Ca1-xLaxFeAs2 single crystal (x ~ 0.18). The obtained Hc2 bears a moderate anisotropy gamma of approximately 2-4.2, located between those of '122' Ba1-xKxFe2As2 (1 < gamma < 2) and '1111' NdFeAsO1-xFx (5 < gamma < 9.2). Both the magnitude of U0 and its field dependence are very similar to those of NdFeAsO1-xFx, also indicating anisotropic superconductivity. Moreover, high and anisotropic Jc's exceeding 10^5 A/cm2 have been calculated from the magnetization hysteresis loops, indicating the existence of strong bulk-dominated pinning in the present superconducting material.