Synthesis and Anisotropic Magnetic Properties of LiCrTe${}_2$ Single Crystals with a Triangular-Lattice Antiferromagnetic Structure

We report on the synthesis of LiCrTe${}_2$ single crystals and on their anisotropic magnetic properties. We have obtained these single crystals by employing a Te/Li-flux synthesis method. We find LiCrTe${}_2$ to crystallize in a TlCdS${}_2$ -type structure with cell parameters of $a$ = 3.9512(5) Å and $c$ = 6.6196(7) Å at $T$ = 175 K. The content of lithium in these crystals was determined to be near stoichiometric by means of neutron diffraction. We find a pronounced magnetic transition at $T_{\mathrm{N}}^{\mathrm{a}\mathrm{b}}$ = 144 K and $T_{\mathrm{N}}^{\mathrm{c}}$ = 148 K, respectively. These transition temperatures are substantially higher than earlier reports on polycrystalline samples. We have performed neutron powder diffraction measurements that reveal that the long-range low-temperature magnetic structure of single crystalline LiCrTe${}_2$ is an A-type antiferromagnetic (AFM) structure. Our DFT calculations are in good agreement with these experimental observations. We find the system to be easy axis with moments oriented along the $c$-direction experimentally as well as in our calculations. Thereby, the magnetic Hamiltonian can be written as $H=H_{\mathrm{H}\mathrm{e}\mathrm{i}\mathrm{s}\mathrm{e}\mathrm{n}\mathrm{b}\mathrm{e}\mathrm{r}\mathrm{g}}+{\sum }_i{K}_c(S_i^z{)}^2$ with $K_c=-0.34K$ (where $\mathrm{\mid }{S}^z\mathrm{\mid }=\frac{3}{2}$). We find LiCrTe${}_2$ to be highly anisotropic, with a pronounced metamagnetic transition for $H\perp ab$ with a critical field of $\mu H_{MM}$(5 K) $\approx$ 2.5 T. Using detailed orientation-dependent magnetization measurements, we have determined the magnetic phase diagram of this material. Our findings suggest that LiCrTe${}_2$ is a promising material for exploring the interplay between crystal structure and magnetism, and could have potential applications in spin-based 2D devices.