Critical behavior, magnetic phase diagram, and magnetic entropy change of MnSb2Te4

The magnetic properties of single-crystal ${\mathrm{MnSb}}_{2}{\mathrm{Te}}_{4}$ were thoroughly investigated. The $M(T)$ 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 $\ensuremath{\beta}=0.441(9)$ with ${T}_{C}=19.4(1)$ K and $\ensuremath{\gamma}=1.108(13)$ with ${T}_{C}=19.3(1)$ K are acquired by the modified Arrott plots, whereas $\ensuremath{\delta}=3.52(1)$ is achieved by a critical isotherm analysis at ${T}_{C}=19.4 \mathrm{K}$, exhibiting three-dimensional critical behavior and complex magnetic interaction. A detailed $H\text{\ensuremath{-}}T$ phase diagram containing antiferromagnetic, canted antiferromagnetic, and ferromagnetic states is constructed, where two triple points ($\ensuremath{\sim}310$ Oe at 19.4 K and $\ensuremath{\sim}1970$ Oe at 19.4 K) are achieved. Additionally, the magnetic entropy change $\mathrm{\ensuremath{\Delta}}{S}_{M}$ is evaluated with $\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{M}^{\text{max}}$ reaching 2.20 J ${\mathrm{kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ in the $ab$ plane and 2.20 J ${\mathrm{kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ along the $c$ axis at $H=70$ kOe. The rotating magnetic entropy change $\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{M}^{R}(T,H)$ is $\ensuremath{\sim}0 \mathrm{J} {\mathrm{kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ at $T>$ 39 K, displaying a nearly isotropic behavior well above ${T}_{C}$, consistent with the above Curie-Weiss fitting; and $\ensuremath{-}\mathrm{\ensuremath{\Delta}}{S}_{M}^{R}$ is less than 0.24 J ${\mathrm{kg}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ at low temperature, demonstrating weak anisotropy.