Development of L10 FePd thin films with large bulk perpendicular magnetic anisotropy and a low damping constant may permit superior scaling of next-generation ultra-high density magnetic memory elements. The buffer layer influences the L10-order parameter, static and dynamic magnetic properties of FePd and demands consideration for the design of high anisotropy strength and low damping films. In this report, we systematically investigate the perpendicular magnetic anisotropy and damping constant of the FePd thin films engineered through the Cr/(Pt, Ru, Ir, Rh), Mo/Ir, and Ir buffer layers. We observed that the Ir(001), Cr(001)/Ir(001), Cr(001)/Pt(001), Cr(001)/Rh(001), and Cr(001)/Ru(001) buffer layers can induce highly oriented (001) FePd films while the Mo/Ir buffer layer does not. Of all the buffer layers, the largest perpendicular magnetic anisotropy Ku ∼1.2 MJ/m3 and damping constant α ∼0.005 were achieved for the Cr/Pt buffered FePd sample, consistent with a high ordering parameter S ∼0.82. The Cr/Ru buffered FePd sample shows the lowest α ∼0.008, despite having a lower S ∼0.64 and a lower Ku ∼0.9 MJ/m3. These film-level properties would be sufficient for the engineering of devices that require thermally stable, sub-10 nm lateral size elements with low damping for applications of low energy-delay magnetic memory devices.
Bibliographical noteFunding Information:
This work was funded, in part, by DARPA HR001117S0056-FP-042 “Advanced MTJs for computation in and near random access memory” and NIST. Additional measurement support was provided by the CharFac of the University of Minnesota and the NIST Nanofabrication Facility. We acknowledge fruitful discussions with B. Kirby (NIST) and M. Shi (Rigaku).