  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 (FMR) linewidths of 41
Oe are demonstrated, some ~ 5-10 % lower than the previous minimum reported for
molecular beam epitaxially (MBE) 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 MHz (alpha = 0.0027) and extrinsic 50 Mhz.
Swept frequency measurements indicate the potential for integrated frequency
domain devices with Q>100 at 30-40 Ghz.
