Study of magnetic, structural and magnetocaloric properties of La_0.6Pr_0.4Mn₂Si₂ under high pressures and magnetic field

The structural, magnetic and magnetocaloric properties of La_0.6Pr_0.4Mn₂Si₂ compound were measured in wide range of temperature, magnetic field and hydrostatic pressure. The structural study up to 10 GPa confirmed the existence of critical Mn-Mn distance 0.2883 nm for the ferromagnetic to antiferromagnetic transition at room temperature. The results demonstrated the crucial role of the volume in the suppression of the ferromagnetic phase above the transition temperature T₁=168 K under pressure. The huge pressure shift of the transition temperature T₁, dT₁/dp=230 K/GPa, was observed. Based on our magnetization measurement the low temperature transition at T₂=30 K is connected with reorientation of Mn moment and the rare-earth sublattice is not ordered in this case. The direct magnetocaloric measurement showed moderate values of the adiabatic temperature change connected with the magnetic transition at T_c and T₁ and confirmed the first order character of the transition at T₁ and second order character of the transition at T_c. - Highlights: • The huge pressure shift of the transition temperature dT₁/dp=230 K/GPa was observed. • Ferromagnetic order is suppressed by applying pressure of 1 GPa. • The direct magnetocaloric effect showed moderate values of ΔT_ad.