paper

Anisotropic physical properties and large critical current density in KCa $_{2}$ Fe $_{4}$ As $_{4}$ F $_{2}$ single crystal

arXiv:2006.04478 · doi:10.1103/PhysRevMaterials.4.104801

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 $I ¨ _{c} / I ¨ _{ab}$ > 100, and semiconductor-like $I ¨ _{c}$ 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.

23 pages, 10 figures

Anisotropic physical properties and large critical current density in KCa2​Fe4​As4​F2​ single crystal

Abstract

Anisotropic physical properties and large critical current density in KCa $_{2}$ Fe $_{4}$ As $_{4}$ F $_{2}$ single crystal