Critical behavior, magnetic phase diagram, and magnetic entropy change of ${\mathrm{MnSb}}_2{\mathrm{Te}}_4$

The magnetic properties of single-crystal ${\mathrm{MnSb}}_2{\mathrm{Te}}_4$ were thoroughly investigated. The $M\left(T\right)$ curves exhibit anisotropic magnetic behaviors with the $c$ axis as the easy axis in low temperature, while Curie-Weiss fitting curves show an isotropic behavior at high temperature. The evaluated Rhodes-Wohlfarth ratio of 2.25 (2.22) for $H//ab$ $(H//c)$ demonstrates an itinerant high-field ferromagnetic state. Critical exponents $\beta =0.441\left(9\right)$ with $T_C=19.4\left(1\right)$ K and $\gamma =1.108\left(13\right)$ with $T_C=19.3\left(1\right)$ K are acquired by the modified Arrott plots, whereas $\delta =3.52\left(1\right)$ is achieved by a critical isotherm analysis at $T_C=19.4 K$, exhibiting three-dimensional critical behavior and complex magnetic interaction. A detailed $H\text{−}T$ phase diagram containing antiferromagnetic, canted antiferromagnetic, and ferromagnetic states is constructed, where two triple points ($\sim 310$ Oe at 19.4 K and $\sim 1970$ Oe at 19.4 K) are achieved. Additionally, the magnetic entropy change $\Delta S_M$ is evaluated with $-\Delta S_M^{\text{max}}$ reaching 2.20 J ${\mathrm{kg}}^{-1}{K}^{-1}$ in the $ab$ plane and 2.20 J ${\mathrm{kg}}^{-1}{K}^{-1}$ along the $c$ axis at $H=70$ kOe. The rotating magnetic entropy change $-\Delta S_M^R(T,H)$ is $\sim 0 J {\mathrm{kg}}^{-1}{K}^{-1}$ at $T>$ 39 K, displaying a nearly isotropic behavior well above $T_C$, consistent with the above Curie-Weiss fitting; and $-\Delta S_M^R$ is less than 0.24 J ${\mathrm{kg}}^{-1}{K}^{-1}$ at low temperature, demonstrating weak anisotropy.