Температурно-барические особенности магнитных характеристик в системах со структурными переходами типа смещения

Using pnictides MnAs and germaindes Mn0.89Cr0.11NiGe as an example, the transformation of thermobaric features of their magnetic characteristics at high pressures is considered. A unified approach is used to describe paramagnetic (PM) structural transitions of the displacement type with a change in the symmetry PM(P63/mmc)-PM(Pnma) from hexagonal to orthorhombic. It is shown that the competition between the parameters of the structural and magnetic orders in both systems manifests itself differently in the stabilization and alternation of the so-called high-spin and low-spin magnetically ordered states initiated by pressure. As a consequence, the structural contribution in these systems weakens (MnAs) or enhances (Mn0.89Cr0.11NiGe ) the giant magnetocaloric effect in the temperature-baric region of the first-order magnetostructural phase transitions.