Ferromagnetic semiconductor Ge1―x―ySnxMnyTe with phase transformation of ferroelectric type

It is expected that joint existence of ferromagnetic properties and ferroelectric structural phase transition in diluted magnetic semiconductors IV-VI leads to new possibilities of these materials. Temperature of ferroelectric transition for such crystals can be tuned by the change of Sn/Ge ratio. Magnetic susceptibility, Hall effect, resistivity and thermoelectric power of Ge1-x-ySnxMnyTe single crystals grown by Bridgeman method (x=0.083-0.115; y=0.025-0.124) were investigated within 4.2-300 K. An existence of FM ordering at TC50 K probably due to indirect exchange interaction between Mn ions via degenerated hole gas was revealed. A divergence of magnetic moment temperature dependences at TTC in field-cooled and zero-field-cooled regimes is obliged to magnetic clusters which are responsible for superparamagnetism at T > TCapprox Tf (freezing temperature) and become ferromagnetic at TC arranging spin glass state at T < Tfapprox TC. Phase transition of ferroelectric type at Tapprox 46 K was revealed. Anomalous Hall effect which allows to determine magnetic moment was observed.