• Klewe, Christoph
• Khodadadi, Behrouz
• Arenholz, Elke
• Shafer, Padraic
• Hwang, Harold Y.
• Yi, Di
• Balakrishnan, Purnima P.
• Urwin, Brittany T.
• Crossley, Sam
• Howe, Brandon M.
• Wisser, Jacob J.
• Mahalingam, Krishnamurthy
• Ndiaye, Alpha T.
• Emori, Satoru

Abstract

Pure spin currents, unaccompanied by dissipative charge flow, are essential for realizing energy-efficient nanomagnetic information and communications devices. Thin-film magnetic insulators have been identified as promising materials for spin-current technology because they are thought to exhibit lower damping compared with their metallic counterparts. However, insulating behavior is not a sufficient requirement for low damping, as evidenced by the very limited options for low-damping insulators. Here, we demonstrate a new class of nanometer-thick ultralow-damping insulating thin films based on design criteria that minimize orbital angular momentum and structural disorder. Specifically, we show ultralow damping in <20 nm thick spinel-structure magnesium aluminum ferrite (MAFO), in which magnetization arises from Fe3+ ions with zero orbital angular momentum. These epitaxial MAFO thin films exhibit a Gilbert damping parameter of ∼0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half-maximum linewidths of ∼0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.

Topics

• impedance spectroscopy
• thin film
• Magnesium
• Magnesium
• aluminium
• magnetization