Ultralow Damping in Nanometer-Thick Epitaxial Spinel Ferrite Thin Films

作者：Emori Satoru; Yi Di; Crossley Sam; Wisser Jacob J; Balakrishnan Purnima P; Khodadadi Behrouz; Shafer Padraic; Klewe Christoph; N'Diaye Alpha T; Urwin Brittany T; Mahalingam Krishnamurthy; Howe Brandon M; Hwang Harold Y; Arenholz Elke; Suzuki Yuri

来源：Nano Letters, 2018, 18(7): 4273-4278.

DOI：10.1021/acs.nanolett.8b01261

• Spinel ferrite
• epitaxy
• Gilbert clamping
• ferromagnetic resonance

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 similar to 0.0015 and negligible inhomogeneous linewidth broadening, resulting in narrow half width at half maximum linewidths of similar to 0.6 mT around 10 GHz. Our findings offer an attractive thin-film platform for enabling integrated insulating spintronics.

• 出版日期2018-7