Enhanced thermo-spin effects in iron-oxide/metal multilayers

Since the discovery of the spin Seebeck effect (SSE), much attention has been devoted to the study of the interaction between heat, spin, and charge in magnetic systems. The SSE refers to the generation of a spin current upon the application of a thermal gradient and detected by means of the inverse spin Hall effect. Conversely, the spin Peltier effect (SPE) refers to the generation of a heat current as a result of a spin current induced by the spin Hall effect. Here we report a strong enhancement of both the SSE and SPE in Fe3O4/Pt multilayered thin films at room temperature as a result of an increased thermo-spin conversion efficiency in the multilayers. These results open the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics.This work was supported by ERATO ‘Spin Quantum Rectification Project’ (Grant No. JPMJER1402) and PRESTO ‘Phase Interfaces for Highly Efficient Energy Utilization’ (Grant No. JPMJPR12C1) from JST, Japan; Grantin-Aid for Scientific Research (A) (Grant No. JP15H02012) and Grant-in-Aid for Scientific Research on Innovative Area, ‘Nano Spin Conversion Science’ (Grant No. JP26103005) from JSPS KAKENHI, Japan, the NEC Corporation, and the Noguchi Institute. The microscopy works were conducted in the Laboratorio de Microscopías Avanzadas at INA, Universidad de Zaragoza; H2020-MSCA-RISE-2016 SPICOLOST (Grant No. 734187); the Spanish Ministry of Economy and Competitiveness (Grant No. MAT2017-82970-C2, including FEDER), Spain; and the Aragón regional government (E26), Spain.Peer reviewe