Magnetic field-induced martensitic transformation and large magnetoresistance in NiCoMnSb alloys

Magnetic field-induced martensitic transformation was realized in Ni50-xCoxMn39Sb11 alloys. The partial substitution of Co for Ni has turned the antiferromagnetically aligned Mn moments in the starting material Ni50Mn39Sb11 into a ferromagnetic ordering, raising the magnetization at room temperature from 8 emu/g for NiMnSb to similar to 110 emu/g for Ni41Co9Mn39Sb11. In the same quaternary sample, a magnetization difference up to 80 emu/g was measured across the martensitic transformation, and the transformation temperature (T-0=259 K) could be lowered by 35 K under a field of 10 T. Also a magnetoresistance over 70% was observed through this field-induced transformation. (c) 2007 American Institute of Physics.