Magnetic phase diagram of Cr1-xMnxGe

Detailed dc magnetic measurements were made on the Cr 1- x Mn x Ge 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 dotuble transition from a paramagnetic to a ferrornagnetic 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.