Surface anisotropy of permalloy in NM∕NiFe∕NM multilayers

We measure surface anisotropy in permalloy (Py) deposited between two layers of normal metal (NM=Ag, Cu, or Ta) by measuring the total perpendicular anisotropy with the angular dependence of the ferromagnetic resonance (FMR) field in a resonant cavity. Comparisons are made with the frequency dependence of a broadband FMR technique and vibrating sample magnetometry, and neither match the sensitivity and range of the cavity technique. We see there is a difference between the surface anisotropy at the interfaces: Py–Ta has a surface anisotropy of (0.078±0.009)mJ∕m2 and the Py–Ag and Py–Cu interfaces have surface anisotropies of (0.10±0.007)mJ∕m2.