Signature of Rashba–Edelstein-mediated charge-to-spin conversion at low-dimensional ferromagnetic interface

Spin-orbit torque (SOT) facilitates charge-to-spin conversion, offering technological opportunities for manipulating magnets solely through charge current. Theories underpinning this phenomenon derive from the spin Hall effect (SHE) and the Rashba-Edelstein effect (REE). However, experimentally, discerning their precise contributions remains challenging due to the intricate interplay of the conversion process between SHE and REE. Here, we present a distinct observation of SOT originating from the interface via REE, substantiated by two distinctive temperature dependencies of the SOT components. The field-like contribution to SOT exhibited significant temperature dependence, consistent with REE theories at interfaces, with a temperature-invariant offset caused by SHE. It was facilitated by atomically thin quasi-two-dimensional ferromagnets, where the REE was sufficiently large to be measured. Additionally, we identified similar temperature dependence in the unidirectional magnetoresistance (UMR), verifying that a substantial REE occurred at interfaces, establishing REE as the primal driver of UMR. These findings provide an experimental framework to determine the REE contribution, highlighting its significant role in magnetic materials, especially as the system size diminishes and interfacial contributions intensify. This study probes temperature-dependent spin–orbit torque and unidirectional387 magnetoresistance in atomically thin ferromagnetic heterostructures. It reveals a Rashba–388 Edelstein-driven field-like torque linked to nonreciprocal magnetotransport