Neutron depolarization measurements on the reentrant spin-glass bcc Cr-Fe-Mn alloy

Neutron depolarization and diffraction measurements were performed on bcc C r60Fe20Mn20 with the aim of studying the low temperature reentrant spin-gla ss phase. This alloy is reported to undergo successive magnetic transitions as the temperature is lowered, viz, antiferromagnetic, ferromagnetic and s pin glass. Transmitted neutron polarization was measured as a function of t emperature for zero-field-cooled (ZFC) and field-cooled (FC) cases. The tra nsition to a ferromagnetic phase is indicated by a decrease in the polariza tion at T-C similar to 100 K. It exhibits a minimum at 55 K below which it increases and at 14 K, in the spin-glass phase, for the ZFC case it recover s to the paramagnetic value. Large irreversibility and time dependent effec ts are also observed in the spin-glass phase. These results indicate that t he ferromagnetic order which grows below T-C is destroyed in the spin-glass phase at 14 K. Neutron diffraction measurements indicate the presence of a n antiferromagnetic (100) peak below T-N similar to 290 K. The intensity of the (100) peak increases as the temperature is lowered and persists down t o 15 K. The low temperature phase is, therefore, a mixed phase where spin-g lass and antiferromagnetic order coexist.