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arXiv · 2403.07254

Negative orbital Hall effect in Germanium

E. Santos·J. E. Abrao·J. L. Costa·J. G. S. Santos·J. B. S. Mendes·A. Azevedo
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Abstract

Our investigation reveals a groundbreaking discovery of a negative inverse orbital Hall effect (IOHE) in Ge thin films. We employed the innovative orbital pumping technique where spin-orbital coupled current is injected into Ge films using YIG/Pt(2)/Ge($t_{Ge}$) and YIG/W(2)/Ge($t_{Ge}$) heterostructures. Through comprehensive analysis, we observe significant reductions in the signals generated by coherent (RF-driven) and incoherent (thermal-driven) spin-orbital pumping techniques. These reductions are attributed to the presence of a remarkable strong negative IOHE in Ge, showing its magnitude comparable to the spin-to-charge signal in Pt. Our findings reveal that although the spin-to-charge conversion in Ge is negligible, the orbital-to-charge conversion exhibits large magnitude. Our results are innovative and pioneering in the investigation of negative IOHE by the injection of spin-orbital currents.

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E. Santos, J. E. Abrao, J. L. Costa, J. G. S. Santos, J. B. S. Mendes, A. Azevedo. 2024-03-12. Negative orbital Hall effect in Germanium. https://doi.org/10.1103/physrevapplied.22.064071

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