Spin glass behavior and magnetocaloric effect in amorphous alloys Ce2Fe23−xMnxB3

Abstract

The magnetic properties and magnetocaloric effect of amorphous alloys Ce2Fe23−xMnxB3 (1≤x≤6) were investigated. The magnetic properties are sensitive to the composition. For samples with x≤3, the low fraction and isolated Fe–Mn antiferromagnetic (AFM) coupling simply align antiparallel to the majority ferromagnetic (FM) order and reduce the total magnetization but cause no noncollinearity; thus they are typical FM materials with TC decreasing drastically from 336 to 226 K and the magnetization has a sharp drop around respective TC without thermal hysteresis suggesting a second order phase transition resulting from their amorphous nature. For x=4 and 5, amorphous alloys Ce2Fe23−xMnxB3 experience two transitions: first a paramagnetic (PM)-FM second transition at 143 and 81 K, respectively, and then a FM–spin glass (SG) transition. A PM-SG transition occurs at the freezing temperature (Tf) about 28.2 K for x=6. The SG behavior in amorphous alloy Ce2Fe23−xMnxB3 can be attributed to the disordered structure resulting from their amorphous nature and the competition between the Fe–Fe FM coupling and Fe–Mn AFM negative coupling. The magnetic entropy change for alloys Ce2Fe23−xMnxB3 with x≤3 is calculated using the Maxwell relation.