Observation of Rashba Magnetism in Ultrathin Ferromagnet-Heavy Metal Bilayers

TL;DR

This study demonstrates Rashba magnetism in ultrathin ferromagnet-heavy metal bilayers, revealing interfacial spin-orbit effects that influence magnetic properties and could advance spin-orbitronic device development.

Contribution

It provides experimental evidence of Rashba magnetism in ultrathin bilayers and links interfacial spin-orbit interaction to novel magnetic states.

Findings

Anomalous temperature- and bias-dependent magnetic behaviors near Curie temperature.

Interfacial spin-orbit interaction induces a Rashba magnetic state.

Potential for controlling spin-orbit phenomena in heterostructures.

Abstract

Both magnetism and spin-orbit coupling in systems with broken inversion symmetry lift the spin degeneracy of electronic bands, but the consequences of interplay between these mechanisms remain poorly understood. Here, we show that ultrathin transition ferromagnet-heavy metal bilayers exhibit anomalous temperature- and electric bias-dependent behaviors in the vicinity of the Curie temperature, inconsistent with the usual Weiss magnetism. Characterization by several complementary techniques and analysis of the dependence on composition reveal that these effects originate from interfacial spin-orbit interaction, which results in the emergence of a state with distinct magnetic and magnetoelectronic properties that can be described as Rashba magnetism. Our findings open a new route for the characterization and control of spin-orbit phenomena in heterostructures enabling the development of efficient spin-orbitronic devices.