Structural and magnetic phase transitions in MnTe–MnSe solid solutions

Neutron diffraction studies as a function of temperature on solid solutions of MnSe and MnTe in the Se rich region are presented. Interestingly as Te is doped in MnSe, the structural transformation to NiAs phase diminishes, both in terms of % fraction of compound as well as in terms of transition temperature. In MnTe0.3Se0.7, the NaCl to NiAs phase transformation occurs at about 40K and although it is present at room temperature in MnTe0.5Se0.5, its volume fraction is only about 10% of the total volume of sample. The magnetic ordering temperature of the cubic phase decreases with increasing Te content while the hexagonal phase orders at the same temperature as in MnSe. Anomalies in thermal evolution of lattice parameters at magnetic ordering as well as structural transition temperatures indicate the presence of magnetostructural coupling in these compounds. •Crystal and magnetic structure of Se rich MnTexSe1−x have been studied using neutron diffraction.•The sample with x=0.5 is close to room temperature structural phase transition boundary between NaCl type cubic to NiAs type hexagonal phase.•NiAs phase is absent in MnTe0.3Se0.7 at higher temperatures and only appears at temperatures below 40K.•A unique relationship exists between the lattice parameters of the cubic NaCl and hexagonal NiAs phases which is responsible for the absence of NiAs phase at higher temperatures.