Revealing the Dominance of the Orbital Hall Effect over Spin in Transition Metal Heterostructures

TL;DR

This study demonstrates that in transition metal heterostructures, the orbital Hall effect significantly surpasses the spin Hall effect in charge conversion, highlighting the importance of orbitronics in condensed matter physics.

Contribution

It provides experimental evidence that the orbital Hall effect dominates over the spin Hall effect in transition metals, supported by first-principles calculations.

Findings

Orbital Hall effect overwhelmingly dominates spin Hall effect.

Results largely agree with first-principles predictions.

Discrepancies observed in select materials.

Abstract

We study inverse spin and orbital Hall effects in 19 transition metals using spin-pumping driven by ferromagnetic resonance. Spin-to-charge conversion was measured in YIG/X(5), while orbital-to-charge conversion was probed in YIG/Pt(2)/X(5) heterostructures. Here, X represents the different transition metals. Surprisingly, the orbital contribution overwhelmingly dominates over the spin response, clarifying the challenge of disentangling these effects. Our results largely agree with first-principles predictions for spin and orbital Hall conductivities but reveal discrepancies in select materials. These findings emphasize the fundamental role of the orbital Hall effect, and position orbitronics as a pivotal frontier in condensed matter physics.