Martensitic transformation and magnetoresistance in Ni40Mn44-xCoxAl16 Heusler alloys

Abstract

In this work, we focus on the magnetic properties and martensitic transformation behaviors in Ni40Mn44-xCoxAl16 (x = 5, 7) Heusler alloys. By partial substitution of Co for Mn, the martensitic transformation (MT) can be tuned in a wide temperature range and shifts to the higher temperature with the increase of Co content in these alloys. The reverse MT can be induced by magnetic field from the weak-magnetic martensite phase to ferromagnetic austenite phase in these alloys. The large magnetoresistance effect of −46.39% and −41.75% are acquired under 90 kOe for Ni40Co5Mn39Al16 and Ni40Co7Mn39Al16 alloys, respectively. The Ni40Mn44-xCoxAl16 alloys with large low-field magnetoresistance and low cost show promising applications for multifunctional materials.