Low damping in epitaxial sputtered iron films

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 34 GHz ferromagnetic resonance linewidths of 41 +/- 2 Oe are demonstrated, some similar to 5%-10% lower than the previous minimum reported for molecular beam epitaxially deposited Fe. Intrinsic and extrinsic damping have been separated over 0-40 GHz, giving a lower bound for intrinsic LL(G) relaxation rates of lambda or G=85 +/- 5 MHz (alpha=0.0027 +/- 0.0001) and for extrinsic eta similar to 30-50 MHz. Swept-frequency measurements indicate the potential for integrated frequency domain devices with Q > 100 at 30-40Ghz. (c) 2006 American Institute of Physics.