Conductivity and the Microwave Properties of 81-Permalloy Thin Films (Correspondence)

The microwave properties of 81-Permalloy (81 percent nickel-19 percent iron) films less than 1050 /spl Aring/ thick and without an external magnetic field have been studied at 10 GHz. The measured dc conductivity values /spl sigma//sub m/ were approximately one-half the values (/spl sigma//sub m/) predicted by the Fuchs-Sondheimer (F-S) theory for monovalent metals, and an indirect check was obtained by comparing measured reflection and transmission coefficients (R and T) with values calculated using /spl sigma//sub m/ and /spl sigma//sub s/. The power transmission coefficient was obtained from the insertion loss, and calculated values of insertion loss using /spl sigma//sub m/ agreed within 2 percent with directly measured values. Calculated values of R using /spl sigma//sub m/ showed good agreement with directly measured values for film thicknesses less than 300 /spl Aring/, but with thicknesses between 300 /spl Aring/ and 1050 /spl Aring/ the directly measured values of R were up to 5 percent smaller than those predicted using /spl sigma//sub m/. Using the F-S conductivity, calculated values of T were approximately an order of magnitude lower than directly measured values, and calculated values of R were as much as 13 percent higher than directly measured values.