Magnetic Proximity Effect in Pt/CoFe2O4 Bilayers

TL;DR

This study demonstrates the magnetic proximity effect in Pt/CoFe2O4 bilayers, revealing induced ferromagnetism in platinum through magnetoresistance measurements, supported by theoretical calculations and control experiments, highlighting potential for spintronic applications.

Contribution

First experimental observation of magnetic proximity effect in Pt/spinel ferrite bilayers using angle-dependent magnetoresistance and theoretical validation.

Findings

Induced ferromagnetism observed in Pt layer at 5 K.

Control experiments confirm the proximity-induced magnetism.

Potential for spin manipulation in spinel ferrite materials.

Abstract

We observe the magnetic proximity effect (MPE) in Pt/CoFe2O4 bilayers grown by molecular beam epitaxy. This is revealed through angle-dependent magnetoresistance measurements at 5 K, which isolate the contributions of induced ferromagnetism (i.e. anisotropic magnetoresistance) and spin Hall effect (i.e. spin Hall magnetoresistance) in the Pt layer. The observation of induced ferromagnetism in Pt via AMR is further supported by density functional theory calculations and various control measurements including insertion of a Cu spacer layer to suppress the induced ferromagnetism. In addition, anomalous Hall effect measurements show an out-of-plane magnetic hysteresis loop of the induced ferromagnetic phase with larger coercivity and larger remanence than the bulk CoFe2O4. By demonstrating MPE in Pt/CoFe2O4, these results establish the spinel ferrite family as a promising material for MPE and spin manipulation via proximity exchange fields.