Absence of magnetic proximity effects in magnetoresistive Pt/CoFe2O4 hybrid interfaces

Abstract

Ultra-thin Pt films grown on insulating ferrimagnetic CoFe2O4 (111) epitaxial films display a magnetoresistance upon rotating the magnetization of the magnetic layer. We report here X-ray magnetic circular dichroism (XMCD) recorded at Pt-L2,3 and Pt-M3 edges. The results indicate that the Pt magnetic moment, if any, is below the detection limit (< 0.001 μ${}_B$/Pt), thus strongly favoring the view that the presence of CoFe2O4 does not induce the formation of magnetic moments in Pt. Therefore, the observed magnetoresistance cannot be attributed to some sort of proximity-induced magnetic moments at Pt ions and subsequent magnetic-field dependent scattering. It thus follows that either bulk (spin Hall and Inverse spin Hall Effects) or interface (Rashba) spin-orbit related effects dominate the observed magnetoresistance. Furthermore, comparison of bulk magnetization and XMCD data at (Fe,Co)-L2,3 edges suggests the presence of some spin disorder in the CoFe2O4 layer which may be relevant for the observed anomalous non-saturating field-dependence of spin Hall magnetoresistance.

14 pages, 5 figures PDF of revised manuscript as finally accepted for publication in Phys. Rev. B

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• Magnetoresistance in Hybrid Pt/CoFe2O4 Bilayers Controlled by Competing Spin Accumulation and Interfacial Chemical Reconstruction
• Interface-induced anomalous Nernst effect in Fe3O4/Pt-based heterostructures
• Absence of magnetic-proximity effect at the interface of Bi${}_2$Se${}_3$ and (Bi,Sb)${}_2$Te${}_3$ with EuS
• Disclosing the nature of asymmetric interface magnetism in Co/Pt multilayers
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• Charge-Spin Interconversion in Epitaxial Pt Probed by Spin-Orbit Torques in a Magnetic Insulator
• Static magnetic proximity effects and spin Hall magnetoresistance in Pt/Y${}_3$Fe${}_5$O${}_{12}$ and inverted Y${}_3$Fe${}_5$O${}_{12}$/Pt bilayers
• Growth and characterization of ultrathin cobalt ferrite films on Pt(111)
• Coherent Epitaxial Semiconductor-Ferromagnetic Insulator InAs/EuS Interfaces: Band Alignment and Magnetic Structure