Anisotropy in transport and magnetic properties ofK0.64Fe1.44Se2

Abstract

We report a study of the anisotropy in transport and magnetic properties of ${\mathrm{K}}_{0.64}$Fe${}_{1.44}$Se${}_{2.00}$ single crystals. The anisotropy in resistivity is up by one order of magnitude between 1.8 and 300 K. The magnetic susceptibility exhibits weak temperature dependence in the normal state with no significant anomalies with decreasing temperature. The lower critical fields ${H}_{c1}$ of ${\mathrm{K}}_{0.64}$Fe${}_{1.44}$Se${}_{2.00}$ are only about 3 Oe and the anisotropy of ${H}_{c1,c}$/${H}_{c1,\mathit{ab}}$ is about 1. The critical currents for $H$$\ensuremath{\Vert}$$\mathit{ab}$ and $H$$\ensuremath{\Vert}$$c$ are about 10--10${}^{3}$ A/cm${}^{2}$, which is smaller than in iron pnictides and in FeTe${}_{1\ensuremath{-}x}$Se${}_{x}$, and nearly isotropic.