Observation of longitudinal spin-Seebeck effect in cobalt-ferrite epitaxial thin films
コバルトフェライトのエピタキシャル薄膜における縦型スピンゼーベック効果の観測
新関 智彦*; 吉川 貴史*; 内田 健一*; 岡 美嶺人*; 鈴木 和也*; 柳原 英人*; 喜多 英治*; 齊藤 英治
Niizeki, Tomohiko*; Kikkawa, Takashi*; Uchida, Kenichi*; Oka, Mineto*; Suzuki, Kazuya*; Yanagihara, Hideto*; Kita, Eiji*; Saito, Eiji
The longitudinal spin-Seebeck effect (LSSE) has been investigated in cobalt ferrite (CFO), an exceptionally hard magnetic spinel ferrite. A bilayer of a polycrystalline Pt and an epitaxially-strained CFO(110) exhibiting an in-plane uniaxial anisotropy was prepared by reactive rf sputtering technique. Thermally generated spin voltage in the CFO layer was measured via the inverse spin-Hall effect in the Pt layer. Externalmagnetic-field () dependence of the LSSE voltage () in the Pt/CFO(110) sample with was found to exhibit a hysteresis loop with a high squareness ratio and high coercivity, while that with shows a nearly closed loop, reflecting the different anisotropies induced by the epitaxial strain. The magnitude of has a linear relationship with the temperature difference (), giving the relatively large / of about 3 V/K for CFO(110) which was kept even at zero external field.