Temperature‐dependent magnetic and synchrotron radiation–based structural study of Fe/Al multilayers

Abstract

This paper shows in situ annealing study of interface reaction of Fe/Al multilayer structure (MLS) grown by ion beam sputtering (IBS). The structural studies with respect to thermal annealing were carried out using synchrotron‐based grazing incidence X‐ray diffraction (GIXRD) and X‐ray reflectivity (XRR), at P08, high‐resolution XRD beamline. In situ annealing was done in a range from 200°C to 400°C. The structural studies show that (1) the pristine MLS consisted of a thin intermixed layer of FeAl at the interfaces formed at the time of deposition, (2) growth of FeAl layer with annealing, and (3) finally converted into a single‐ordered layer of Fe3Al at higher annealing temperature. The effect of thermal annealing on the interfacial structure of MLS is also investigated by using high‐resolution transmission electron microscopy (TEM). The TEM results further confirm the above XRD and XRR results. The magnetization with respect to temperature is recorded using vibrating sample magnetometer (VSM). Coercivity as well as saturation field increases continuously, but the magnetization decreases as a result of annealing. The Curie temperature (Tc) determined from the M‐T curve is found to be very less as compared with Fe bulk but much higher than that of room temperature. The magnetization behavior received is largely associated to change in MLS structure, FeAl phase formation, and enhancement in antiferromagnetic interlayer coupling with respect to thermal annealing.