Magnetic Phase Diagram of Cr_1–xMn_xGe

Detailed dc magnetic measurements were made on the Cr_1–xMn_xGe alloy system with 0≤x≤0.60 in the temperature range from 4.2 K to 420 K. The alloy system is paramagnetic for 0≤x≤0.06. For 0.09≤x≤0.15 ferromagnetism appears at low temperatures. The system with 0.17≤x≤0.21 shows a double transition from a paramagnetic to a ferromagnetic state at lower temperatures and finally to a mixed phase of ferromagnetic and spin glass ordering. For 0.24≤x≤0.60 spontaneous magnetiztion disappears and a normal spin glass phase is observed. A variety of phase transitions observed in the present alloy system are attributed to the competition between the positive contribution from modified RKKY interaction and the negative contribution from direct exchange interaction to the Mn-Mn exchange interaction.