Inverse Altermagnetic Spin Splitting Effect-Induced Terahertz Emission in RuO_2

摘要

The relativistic inverse spin Hall effect (ISHE) plays a pivotal role in terahertz(THz) emission in magnet/heavy metal bilayers. Here, THz emission fromRuO_2/Py bilayers is reported due to not only the relativistic ISHE but also thenonrelativistic inverse altermagnetic spin splitting effect (IASSE) in RuO_2. Forthe (100)-oriented RuO_2/Py bilayers, the THz emission is greatly enhancedowing to IASSE once the polarization direction of the spin current (from the Pylayer induced by pump laser) is parallel to the Néel vector of RuO_2, producingthe anisotropic THz emission with twofold symmetry. In contrast, theRuO_2(110)/Py bilayer only exhibits isotropic THz emission because of theabsence of IASSE-induced spin-charge conversion in the (110)-oriented RuO_2films. Apart from the fundamental significance of exploring the IASSE-inducedspin-to-charge conversion, the finding also enriches the physical mechanismand modulation method of THz emission in spintronic systems.