Field-induced tricritical behavior in the Neel-type skyrmion host GaV4S8

The lacunar spinel compound GaV4S8 exhibits a Neel-type skyrmion, which holds great promise for future spintronics and ultrahigh-density magnetic memory devices. To gain more insight into the magnetic interactions, the critical behavior of GaV4S8 is studied by dc magnetization measurement around the Curie temperature (T-C). A set of reliable critical exponents (beta = 0.220 +/- 0.024, gamma = 0.909 +/- 0.005, and delta = 5.161 +/- 0.003) is obtained by the modified Arrott plot technique, the Kouvel-Fisher method, and critical isothermal analysis. The generated critical exponents fulfill the universality class of tricritical mean-field theory, which suggests a field-induced tricritical phenomenon. Based on the scaling equations, boundaries between the skyrmion and ferromagnetic phases can be distinguished. A tricritical point is revealed at the temperature of T-Tr = 12 K and field of H-Tr = 60 mT, which is located at the intersection point among the skyrmion, ferromagnetic, and paramagnetic phases. It is suggested that the origin of the tricritical behavior in GaV4S8 is related to the skyrmion state near the magnetic transition temperature T-C.