Nonlocal Electrical Detection of Reciprocal Orbital Edelstein Effect

TL;DR

This paper experimentally confirms Onsager reciprocity in orbital transport using nonlocal measurements, revealing key properties of orbital decay length and advancing the understanding of orbitronics for long-range device applications.

Contribution

It demonstrates the Onsager reciprocity of orbital transport through nonlocal measurements, providing new insights into orbital decay and nonlocal orbital correlations.

Findings

Confirmed Onsager reciprocity in orbital transport.

Orbital decay length ~100 nm at room temperature, temperature-dependent.

Nonlocal measurement method avoids local measurement limitations.

Abstract

Spin-Orbitronics leverages the spin and orbital degrees of freedom in solids for information processing. The orbital Edelstein effect and orbital Hall effect, where the charge current induces a nonequilibrium orbital angular momentum, offer a promising method to manipulate nanomagnets efficiently using light elements. Despite extensive research, understanding the Onsager reciprocity of orbital transport, fundamentally rooted in the second law of thermodynamics and time-reversal symmetry, remains elusive. In this study, we experimentally demonstrate the Onsager reciprocity of orbital transport in an orbital Edelstein system by utilizing nonlocal measurements. This method enables the precise identification of the chemical potential generated by orbital accumulation, avoiding the limitations associated with local measurements. Remarkably, we observe that the direct and inverse orbital-charge conversion processes produce identical electric voltages, confirming Onsager reciprocity in orbital transport. Additionally, we find that the orbital decay length, approximately 100 nm at room temperature, is independent of Cu thickness and decreases with lowering temperature, revealing a distinct contrast to spin transport behavior. Our findings provide valuable insights into both the reciprocity of the charge-orbital interconversion and the nonlocal correlation of orbital degree of freedom, laying the ground for orbitronics devices with long-range interconnections.