Low Ghz loss in sputtered epitaxial Fe

TL;DR

This paper demonstrates that sputtered epitaxial iron films exhibit extremely low high-frequency magnetic loss, with FMR linewidths comparable or superior to molecular beam epitaxial films, enabling high-Q microwave devices.

Contribution

It shows that sputtered epitaxial Fe films can achieve record low ferromagnetic resonance linewidths and damping rates, surpassing previous epitaxial methods.

Findings

Minimum 34 GHz FMR linewidths of 41 Oe

Intrinsic damping rate lower bound of 85 MHz

Potential for high-Q frequency domain devices at 30-40 GHz

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 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.