Disentangling Spin and Orbital Contributions in the Search for Altermagnetic Terahertz Conversion in RuO2
Abstract
Rutile RuO2 has emerged as a prominent candidate altermagnet, yet the microscopic origin of its reported charge-angular-momentum conversion remains unsettled. Recent theoretical and experimental advances have highlighted a potentially dominant role of orbital transport, raising a fundamental ambiguity between spin- and orbital-mediated conversion in RuO2. Here, we report the first experimental disentanglement of the spin- and orbital-to-charge conversion channels in RuO2 heterostructures using terahertz emission spectroscopy. We identify Fe as a predominantly spin-current injector, whereas Ni and permalloy predominantly inject orbital currents, revealing a substantial orbital contribution to ultrafast terahertz emission. Under controlled spin-current injection, we find no evidence for inverse altermagnetic spin-splitting effect. Instead, the observed anisotropy is consistent with an anisotropic inverse spin Hall response that is strongly conditioned by the near-interface environment. Under orbital-current injection, the anisotropy is markedly weaker, indicating that orbital-to-charge conversion is largely isotropic in RuO2. Our results establish orbital transport and interface-conditioned spin Hall conversion as key to terahertz emission from RuO2, underscoring the need to disentangle spin, orbital, and interfacial contributions before assigning anisotropy to altermagnetism.
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BibTeX
@misc{liu2026disentangling,
title = {{Disentangling Spin and Orbital Contributions in the Search for Altermagnetic Terahertz Conversion in RuO2}},
author = {Jiahao Liu and Yuxiao Mo and Tongyang Guan and Wenhui Fang and Yongwei Cui and Wentao Qin and Zhe Yuan and Lishu Zhang and Zhensheng Tao and Yizheng Wu},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.09098},
eprint = {2611.09098},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.09098},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Disentangling Spin and Orbital Contributions in the Search for Altermagnetic Terahertz Conversion in RuO2
AU - Jiahao Liu
AU - Yuxiao Mo
AU - Tongyang Guan
AU - Wenhui Fang
AU - Yongwei Cui
AU - Wentao Qin
AU - Zhe Yuan
AU - Lishu Zhang
AU - Zhensheng Tao
AU - Yizheng Wu
PY - 2026
DA - 2026/11/06
PB - arXiv
DO - 10.48550/arxiv.2611.09098
UR - https://arxiv.org/abs/2611.09098
AB - Rutile RuO2 has emerged as a prominent candidate altermagnet, yet the microscopic origin of its reported charge-angular-momentum conversion remains unsettled. Recent theoretical and experimental advances have highlighted a potentially dominant role of orbital transport, raising a fundamental ambiguity between spin- and orbital-mediated conversion in RuO2. Here, we report the first experimental disentanglement of the spin- and orbital-to-charge conversion channels in RuO2 heterostructures using terahertz emission spectroscopy. We identify Fe as a predominantly spin-current injector, whereas Ni and permalloy predominantly inject orbital currents, revealing a substantial orbital contribution to ultrafast terahertz emission. Under controlled spin-current injection, we find no evidence for inverse altermagnetic spin-splitting effect. Instead, the observed anisotropy is consistent with an anisotropic inverse spin Hall response that is strongly conditioned by the near-interface environment. Under orbital-current injection, the anisotropy is markedly weaker, indicating that orbital-to-charge conversion is largely isotropic in RuO2. Our results establish orbital transport and interface-conditioned spin Hall conversion as key to terahertz emission from RuO2, underscoring the need to disentangle spin, orbital, and interfacial contributions before assigning anisotropy to altermagnetism.
ER -