Anomalies of magnetic properties of layered crystals InSe containing Mn

Static magnetic susceptibility and ESR spectra of layered semiconducting InSe crystals containing Mn were investigated. Solid solution In1−XMnXSe is responsible for ferromagnetism at Curie temperature TC > 270 K. Single wide line ESR spectrum was observed. It practically disappeared at 90 K. Paramagnetic constant background of magnetic susceptibility originates from atypical Van-Vleck Mn3+ (d4) ions, which are in a state of nonmagnetic singlet in crystal field, and magnetization of crystals in ferromagnetic state. Very narrow (2 Oe) line with g = 1.999 appears at temperatures lower than 23 K which is apparently due to the electrons localized on the levels of space quantization. Two maxima at ∼ 160 K and ∼ 260 K are observed as the temperature dependence of magnetic susceptibility. They are obliged to inclusions of antiferromagnetic MnSe. At high magnetic fields of 6 and 50 kOe, the first peak widens and disappears.