Observation of the orbital Hall effect in a light metal Ti

TL;DR

This paper reports the first direct experimental observation of the orbital Hall effect in titanium, demonstrating the role of orbital angular momentum in magnetic phenomena and its potential for electric control of magnetism.

Contribution

It provides the first direct detection of the orbital Hall effect in a light metal, supported by Kerr rotation measurements and theoretical calculations.

Findings

Kerr rotation measurements confirm orbital Hall effect in Ti

Orbital torque measurements support the effect's presence

Results suggest orbital angular momentum as a key dynamic degree of freedom

Abstract

The orbital angular momentum is a core ingredient of orbital magnetism, spin Hall effect, giant Rashba spin splitting, orbital Edelstein effect, and spin-orbit torque. However, its experimental detection is tricky. In particular, direct detection of the orbital Hall effect remains elusive despite its importance for electrical control of magnetic nanodevices. Here we report the direct observation of the orbital Hall effect in a light metal Ti. The Kerr rotation by the accumulated orbital magnetic moment is measured at Ti surfaces, whose result agrees with theoretical calculations semiquantitatively and is supported by the orbital torque measurement in Ti-based magnetic heterostructures. The results confirm the electron orbital angular momentum as an essential dynamic degree of freedom, which may provide a novel mechanism for the electric control of magnetism. The results may also deepen the understanding of spin, valley, phonon, and magnon dynamics coupled with orbital dynamics.