Interface-induced anomalous Nernst effect in Fe 3 O 4 /Pt-based heterostructures

We have studied the anomalous Nernst effect (ANE) in [Fe3O4/Pt]-based heterostructures grown at high temperature, by measuring the ANE-induced electric field with a magnetic field applied normal to the sample surface, in the perpendicular magnetized configuration, where only the ANEs from the ferromagnetic layers or magnetic proximity effects can be detected. An ANE voltage is observed for [Fe3O4/Pt]n multilayers, and we further investigated its origin by performing measurements in [Fe3O4/Pt/Fe3O4] trilayers as a function of the Pt thickness. Our results suggest the presence of an interface-induced ANE in the metallic layer, possibly driven by a heat induced subnanometer interdiffusion which affects the nature of the Fe3O4/Pt interface. Despite this ANE, the spin Seebeck effect is the dominant mechanism for the transverse thermoelectric voltage in the in-plane magnetized configuration, accounting for about 70% of the voltage in the multilayers.
This work was supported by the ERATO “Spin Quantum Rectification Project” (Grant No. JPMJER1402) and PRESTO “Phase Interfaces for Highly Efficient Energy Utilization” (Grant No. JPMJPR12C1) from JST, Japan; Grant-in-Aid for Scientific Research (A) (Grant No. JP15H02012), Grant-in-Aid for Scientific Research on Innovative Area, “Nano Spin Conversion Science” (Grant No. JP26103005) and Grant-in-Aid for Research Activity Start-up (No. JP18H05841) from JSPS KAKENHI, Japan; H2020-MSCA-RISE-2016 SPICOLOST (Grant No. 734187); and the Spanish Ministry of Economy and Competitiveness (Grant No. MAT2017-82970-C2, including FEDER) and the Aragon regional government (E26), Spain. The microscopy works were conducted in the LMA at INA, Universidad de Zaragoza. A.A. acknowledges MINECO [through Project Nos. FIS2016-78591-C3-1-R (SKYTRON), PCIN-2015-111 (SOgraph), and SEV-2016-0686] and Comunidad de Madrid through Grant No. S2018/NMT-4321 (NANOMAGCOST-CM).