Structure and giant inverse magnetocaloric effect of epitaxial Ni-Co-Mn-Al films

In the presented work 200 nm thick epitaxial Ni
₄₁
Co
_10.4
Mn
_34.8
Al
_13.8
thin films are studied. The films were deposited on heated MgO(001) substrates by co-sputtering. The structural properties of the films were investigated by atomic force microscopy, temperature dependent X-ray diffraction, and TEM. Magnetic and magnetocaloric properties were analyzed using temperature dependent and isothermal magnetization measurements. The structure of the martensite phase is shown to be an adaptive 14M phase. In order to analyze the metamagnetic characteristic of the martensitic transition of Ni-Co-Mn-Al films, temperature dependent field cooling (FC) and field heating (FH) magnetization curves were measured.