Weak ferrimagnets of the YFe$_{1-x}$Cr$_x$O$_3$ type: negative magnetization and spin reorientation

In this work, we present an analysis of magnetic properties of weak ferrimagnets of the YFe$_{1-x}$Cr$_x$O$_3$ type. Taking into account the main spin interactions – isotropic Heisenberg superexchange, antisymmetric Dzyaloshinskii–Moriya exchange, single-ion spin anisotropy - calculations of the free energy, concentration and temperature dependences of magnetization were carried out within a framework of a molecular field model. In particular, the model demonstrates the phenomena of temperature compensation and negative magnetization, as well as spin reorientation. The compensation temperature reaches room temperature $T$ = 300 K in a composition with $x\approx$ 0.45. The existence of magnetic structures of the $G_{xyz}$ type with the spatial orientation of the Neel vector is predicted.