Unconventional views on orbitronics supported by experimental results

TL;DR

This paper challenges the idea of long-range orbital current transport in orbitronics, providing experimental evidence that local orbit-spin conversions dominate in Ni/(Pt)Ti/Au heterostructures.

Contribution

It presents experimental results showing local orbit-spin conversions rather than long-range orbital transport in orbitronics.

Findings

Charge current is independent of Ti thickness up to 60 nm.

Charge current depends on both Ti interfaces, indicating spin-mediated transport.

Results contradict the assumption of long-range orbital current transport.

Abstract

Emerging orbitronics assumes long-range orbital current transport, analogous to spin currents. However, recent theory and experiments challenge this view, showing rather local characters for orbital polarization and orbit-spin conversions. We study angular momentum generated by ferromagnetic resonance and thermal gradients in Ni/(Pt)Ti/Au heterostructures. The observed charge current produced is independent of Ti thickness up to 60 nm, incompatible with orbital transport in Ti. Instead, its magnitude depends on both Ti interfaces, evidencing spin-mediated transport in between after and before local orbit-spin interconversions.