Magnetic field induced phase transformation in polycrystalline NiCoMnAl thin films

Abstract

NiCoMnAl thin films were deposited onto unheated substrates using dc magnetron co-sputtering. The microstructure of as-deposited films consisted of nanocrystals in an amorphous matrix and did not exhibit a martensitic phase transformation. After heat treatment, films crystallized into a B2 austenite phase, which exhibited a magnetic field induced martensitic phase transformation. The level of the change in the martensitic transformation temperatures in the magnetic field was determined to be ∼2.1 K/T. The films exhibited non-reversible magnetic field induced martensite to austenite transformation due to the large thermal hysteresis. © 2013 AIP Publishing LLC.