Magnetic property improvement of sputter-prepared FePd films on glass substrates with W underlayer

•W underlayer promotes the ordering of FePd film.•W underlayer refines grain size of FePd film.•W underlayer greatly enhances permanent magnetic properties of FePd film.•Significant enhancement in (BH)max about 100% is achieved with W underlayer. Magnetic properties and structure of sputter-prepared FePd thin films on the glass substrates with W underlayer have been studied. The structural analysis shows that FePd films have a (111) preferred orientation. All studied FePd films exhibit in-plane magnetic anisotropy. In the single layer samples, the coercivity (Hc) and magnetic energy product ((BH)max) are increased with Ta and reached the maximum value of 2.3kOe and 4.3MGOe in the sample annealing at 650°C. With further increase of Ta, magnetic properties drop rapidly. Dependence of magnetic hardening on Ta can be explained by dominant solid reactions in different region of Ta including ordering and grain growth. Interestingly, magnetic properties of L10-FePd are largely improved with the insertion of a 5-nm-thick W underlayer. Hc and (BH)max are significantly increased to 3.9kOe and 8.5MGOe, respectively. Structural results suggest that this magnetic enhancement is related to both higher ordering degree and refined microstructure.