Low damping in epitaxial sputtered iron films

Abstract

We show that sputtered, pure epitaxial iron films can have high-frequency loss as low as, or lower than, any known metallic ferromagnetic heterostructure. Minimum 34GHz ferromagnetic resonance linewidths of 41±2Oe are demonstrated, some ∼5%–10% lower than the previous minimum reported for molecular beam epitaxially deposited Fe. Intrinsic and extrinsic damping have been separated over 0–40GHz, giving a lower bound for intrinsic LL(G) relaxation rates of λ or G=85±5MHz (α=0.0027±0.0001) and for extrinsic η∼30–50MHz. Swept-frequency measurements indicate the potential for integrated frequency domain devices with Q>100 at 30–40Ghz.