Inverse Orbital Torque via Spin-Orbital Intertwined States

Bulk and Interface Effects Based on Rashba-like States in Ti and Ru Nanoscale-Thick Films: Implications for Orbital-Charge Conversion in Spintronic Devices

“…To gain deeper insights into the influence of metal layer oxidation, we conducted a comprehensive study involving a range of thin films subjected to controlled and natural oxidation processes. Taking advantage of the well-studied Pt/CuO x interface as a model system to investigate the Rashba-type orbital effect, 27,33 we prepared a series of samples like those used in previous sections, including a naturally oxidized capping layer of copper (Cu). To investigate the optimum thickness of the CuO x capping layer, we prepared a series of samples of YIG/Pt(2)/ Cu(t Cu ) for .…”

“…, where 0 SH Pt > and 0 OH NM > , confirming the theoretical results available in the literature. 21 The experimental data of Figure 3(b) and 3(d) were fitted using the equation 39 where A is a constant, t NM is the thickness of the NM2 material and L represents the orbital diffusion length. From the adjustment to the experimental data, we found nm, or smaller.…”

“…From the adjustment to the experimental data, we found nm, or smaller. 33 According to the literature, 33,41 spin pumping (by SP-FMR or LSSE) in YIG/Pt samples creates a flow of spin angular momentum in Pt, which, due to the strong SOC, is accompanied by a collinear orbital angular momentum flow that can be injected in an adjacent NM2 layer. Although the difference in diffusion lengths between Ti and Ru is small, the significant SOC of Ru compared to Ti could elucidate the larger L of Ru.…”

“…Although the difference in diffusion lengths between Ti and Ru is small, the significant SOC of Ru compared to Ti could elucidate the larger L of Ru. 39,41 This may seem counterintuitive as SOC typically leads to the dissipation of angular momentum. However, as indicated in the literature, 41 the dissipation of S and L is explained by the parameters S and L , respectively, while the additional phenomenological parameter LS describes the nondissipative exchange between orbital and spin angular momentum.…”

“…40 Thus, an increased orbital diffusion length is anticipated in samples with Ru films. However, both models, the phenomenological theory 39,41 and the orbital diffusion theory, 42 need to be confirmed with a first-principles theory that explains orbital relaxation.…”