Magnetostructural transition and adiabatic temperature change in Mn–Co–Ge magnetic refrigerants

Crystal structure, structural and magnetic transitions were investigated in a series of MnCo0.95Gex (x = 0.95, 0.97, 1.0) alloys. A first-order magnetic transition was observed in MnCo0.95Ge0.97 with a large thermal and magnetic hysteresis, while the other two composition alloys undergo a second-order ferromagnetic transition. The adiabatic temperature change for MnCo0.95Ge0.97 strongly relies on the sample history (heating or cooling protocols) due to the competition of structural and magnetic transitions. The structural contribution works against the magnetic contribution to the total magnetocaloric effect.