Anisotropy of magnetic properties in single crystals of CH$_3$NH$_3$PbI$_3$ hybrid perovskites

Hybrid metal-organic CH$_3$NH$_3$PbI$_3$ perovskites are promising materials for photovoltaics and optoelectronics, and the recently discovered magnetic and electrical ordering in them stimulates their potential applications in spintronics. The temperature (in the range of 5–300 K) and magnetic field (up to 50 kOe) dependences of the magnetization of CH$_3$NH$_3$PbI$_3$ single crystals for different directions of the magnetic field are measured. A strong anisotropy of the magnetic properties is found. If the magnetic field is perpendicular to the (001) crystallographic plane, the diamagnetic behavior of the magnetization is observed. If the field is oriented in the (001) plane, a transition from the ferromagnetic state to the paramagnetic state is revealed at a temperature of about 115 K. The features of the magnetic susceptibility observed in the low-temperature range are characteristic of the presence of antiferromagnetic correlations. In addition, in the CH$_3$NH$_3$PbI$_3$ hybrid perovskite, a relation between the magnetic properties and the structural phase transition from the tetragonal to the orthorhombic phase is determined. The effective magnetic moment equals 0.76$\mu_{\text{B}}$ and 0.39$\mu_{\text{B}}$ in the tetragonal and orthorhombic phases, respectively.