The recently predicted mechanism of orbital pumping enables the generation of pure orbital current from a precessing ferromagnet (FM) without the need for electrical current injection. This orbital current can be efficiently injected into an adjacent nonmagnetic material (NM) without being hampered by electrical conductivity mismatch. However, experimentally identifying this novel effect presents significant challenges due to the substantial background contributions from spin pumping and spin rectification effects (SREs). In this work, we disentangle the effects of orbital pumping from spin pumping in bilayer structures composed of Nb/Ni and Nb/Fe60Co20B20 by observing a sign reversal of the measured voltage. This reversal arises from the competing signs of the spin and orbital Hall effects in the Nb. We establish methods to differentiate the pumping signal from SREs by analyzing the distinct angular dependence of the measured voltage and its spatial dependence relative to the radio frequency excitation source.
@article{arxiv.2502.08269,
title = {Identification of orbital pumping from spin pumping and rectification effects},
author = {Nils Keller and Arnab Bose and Nozomi Soya and Elias Hauth and Fabian Kammerbauer and Rahul Gupta and Hiroki Hayashi and Hisanobu Kashiki and Gerhard Jakob and Sachin Krishnia and Kazuya Ando and Mathias Kläui},
journal= {arXiv preprint arXiv:2502.08269},
year = {2025}
}