Determination of magnetic properties of ultrathin iron films using microwave stripline technique

Microwave microstrip line technique is utilized to determine the magnetic p roperties of ultrathin iron (Fe) films. Wideband tunable microwave filters are fabricated, either in integrated or flip-chip type, on ultrathin Fe fil ms grown on GaAs substrates using molecular beam epitaxy. Taking advantage of the ferromagnetic resonance effects of the Fe films, four-fold variation of the resonance frequency is found to relate directly to the tetragonal s ymmetry of in-plane anisotropy. As a result, effective magnetization 4 pi M -eff, four-fold in-plane anisotropy K-1, second order term of perpendicular uniaxial anisotropy K-u perpendicular to, and the Gilbert damping factor o f the ultrathin films are derived from Landau-Lifshitz equation and transmi ssion characteristics of the microwave filters involved. (C) 2000 American Institute of Physics. [S0021-8979(00)16808-2].