Inverse and normal magnetocaloric effects in LaFe12B6

Abstract

Intrinsic magnetic properties and magnetocaloric effect were studied for LaFe12B6 itinerant-electron system, which presents an antiferromagnetic ground state below 36 K. For certain magnetic fields values, LaFe12B6 exhibits a sequence of two successive magnetic transitions: an antiferromagnetic-ferromagnetic (AFM-FM) transition at low temperature followed by a ferromagnetic-paramagnetic transition, leading to normal and inverse magnetocaloric effects, respectively. At finite temperatures, both antiferromagnetic (AFM) and paramagnetic states can be transformed into a ferromagnetic (FM) state via a field-induced metamagnetic transition accompanied with a huge magnetic hysteresis. Moreover, we reveal that, at low temperatures, the magnetization displays abrupt jumps across the first-order AFM-FM transition, giving rise to an unusual and unique staircase-like behavior. LaFe12B6 exhibits both normal magnetocaloric effect around the Curie temperature and large inverse magnetocaloric effect around the AFM-FM transition temperature; for μ0ΔH = 7 T, ΔSM is found to be −6.8 and 19 J kg−1 K−1 around 38 and 8 K, respectively.