Synthesis, anisotropy, and superconducting properties of LiFeAs single crystal

Abstract

A LiFeAs single crystal with $T_c^{onset}$$\sim$19.7 K was grown successfully in a sealed tungsten crucible using the Bridgeman method. The electrical resistivity experiments revealed a ratio of room temperature to residual resistivity (RRR) of approximately 46 and 18 for the in-plane and out-of plane directions. The estimated anisotropic resistivity, $\gamma_\rho$=$\rho_c$ / $\rho_{ab}$, was approximately 3.3 at $T_c^{onset}$. The upper critical fields had large $H_{c2} ^{\shortparallel ab}$ and $H_{c2}^{\shortparallel c}$ values of 83.4 T and 72.5 T, respectively, and an anisotropy ratio is $\gamma_H$=$H_{c2}^{\shortparallel ab}$ / $H_{c2} ^{\shortparallel c}$$\sim$1.15. The high upper critical field value and small anisotropy highlight the potential use of LiFeAs in a variety of applications. The calculated critical current density $(J_c)$ from the $M$-$H$ loop is approximately 10$^3$ A/cm$^2$