Magnetic phase diagram of amorphous Cr_1-xMn_xGe

Measurements of DC magnetic susceptibility and parallel AC susceptibility in DC magnetic fields are made on the amorphous Cr_1-xMn_xGe alloy system with 0<or=x<or=1 in the temperature range 4.2 K-420 K. On the basis of the magnetic measurements, the authors propose a magnetic phase diagram in which there is only one transition from paramagnetic to spin-glass phase in contrast with that for crystalline Cr_1-xMn_xGe, a re-entrant spin-glass system. This difference is attributed to the disappearance of the ferromagnetic contribution from the modified RKKY interaction due to amorphisation. The origin of the spin-glass interaction in the amorphous Cr _1-xMn_xGe system and the variation of the spin-glass properties with composition are also discussed in detail.