Negative spin-to-charge current induced by interfacial spin–orbit coupling in Pt/monolayer 1T-TiSe2/graphene/yttrium iron garnet quadruple heterostructures

Abstract

Strong spin–orbit coupling (SOC) materials and graphene have recently emerged as promising interfacial layers for tailoring spin transport in normal metal/ferromagnet heterostructures. However, spin-to-charge conversion in Pt/two-dimensional (2D) layer/graphene/yttrium iron garnet (YIG) heterostructures remains experimentally unexplored. This study investigates the effects of monolayer graphene and its interfacial coupling with a non-magnetic 2D transition metal dichalcogenide (TMDC) with relatively strong SOC on the longitudinal spin Seebeck effect (LSSE) in Pt/TiSe₂ (or ZrSe₂)/graphene/YIG quadruple heterostructures. Interfacial SOC between TMDC and graphene is demonstrated to induce an additional spin-to-charge conversion channel in the Pt layer, generating a charge current opposite in direction to the conventional inverse spin Hall effect-induced current from YIG and thereby leading to a net suppression of the LSSE signal. Thus, the study highlights the potential of non-magnetic TMDC interlayers for modulating spin transport, offering new design pathways for spintronic devices.