Giant exchange bias in micro-sized magnetic shape memory alloy particles

Abstract

Abstract We report the effects of the magnetic ground sate and microstructure on exchange bias (EB) in ball milled Ni44Co6Mn39.5Sn10.5 alloys. A giant bias field of 1.49 T has been obtained for the micron-sized particles after 15 h milling, which is considerably larger than that of 2 h milled platelets (0.35 T) and that of the bulk alloy (0.12 T). This giant bias field is attributed to the increased volume fraction of antiferromagnetic/ferromagnetic interface, the enhanced antiferromagnetic fraction and the formed agglomerates. Our results reveal the critical roles of the magnetic ground state and microstructure of milled alloys in determining EB.