Anisotropic physical properties and large critical current density in KCa${_2}$Fe${_4}$As${_4}$F${_2}$ single crystal

TL;DR

This study investigates the anisotropic electrical and magnetic properties of KCa₂Fe₄As₄F₂ single crystals, revealing high critical current density and potential for enhanced superconducting applications through microstructural analysis and irradiation techniques.

Contribution

The paper provides a comprehensive analysis of the anisotropic properties and microstructure of KCa₂Fe₄As₄F₂, demonstrating its large critical current density and potential for improved superconducting performance.

Findings

High anisotropy in electrical resistivity (${\rho _c / \rho _{ab}} > 100$)

Large critical current density (${J_c}$) with field-direction dependence

Enhanced ${J_c}$ achievable via heavy-ion irradiation

Abstract

We present a systematic study of electrical resistivity, Hall coefficient, magneto-optical imaging, magnetization, and STEM analyses of KCa${_2}$Fe${_4}$As${_4}$F${_2}$ single crystals. Sharp diamagnetic transition and magneto-optical imaging reveal homogeneity of single crystal and prominent Bean-like penetrations of vortices. Large anisotropy of electrical resistivity, with ${\rho _c / \rho _{ab}}$ > 100, and semiconductor-like ${\rho _c}$ suggest that the electronic state is quasi two-dimensional. Hall effect measurements indicate that KCa${_2}$Fe${_4}$As${_4}$F${_2}$ is a multiband system with holes as main carriers. Magnetization measurements reveal significantly larger J$_c$ compared with that in other iron-based superconductors with different values of J$_c$ depending on the direction of magnetic field. Origin of these J$_c$ characteristics is discussed based on microstructural observations using STEM. In addition, further enhancement of J$_c$ in KCa${_2}$Fe${_4}$As${_4}$F${_2}$ for future application is demonstrated in terms of heavy-ion irradiation.