Evidence of Martensitic Phase Transitions in Boron Substituted Ni-Mn-In Thin Films*

Ni-Mn-In-B thin films were synthesized on Si substrates using ultra-high vacuum magnetron sputtering. Metamagnetic transitions with thermal hysteresis have been observed on 30 nm thin films using the magnetization measurements. The temperature dependences of the magnetization curves were found to be similar to those of the bulk counterpart. Electronic and magnetic properties of Ni-Mn-In-B thin films were studied using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). From the XAS and XMCD spectra, we have observed that Ni plays a dominant role in the overall magnetism. Element-specific XMCD hysteresis loops of Ni in the NiMnInB films were measured as a function of temperature and observed minimum magnetic hysteresis at martensitic transformation. Possible mechanisms responsible for the changes in electronic and magnetic properties of thin films through the effect of redistribution of d electrons are discussed.