Features of magnetic phase transitions in iron-manganese arsenides of the type Fe a−x MnxAs (a≈1.6)

This paper discusses how temperature/pressure processing affects the cascade of magnetic phase transitions in the alloy Fe_0.5Mn_1.1As with a C38 tetragonal crystal lattice. It shows that after various temperature/pressure treatment regimes (quenching of the sample from 800 °C under pressures of 30–60 kbar) no transition to the low-temperature phase is observed, as a result of which the ferrimagnetic phase extends to liquid-nitrogen temperatures. These results are analyzed on the basis of a qualitative model that takes into account the competition of ferromagnetic and antiferromagnetic interactions within and between nonequivalent crystallographic subsystems. Fiz. Tverd. Tela (St. Petersburg) 39, 889–893 (May 1997)