Spin-Current to Charge-Current Conversion and Magnetoresistance in a Hybrid Structure of Graphene and Yttrium Iron Garnet

Abstract

The use of graphene in spintronic devices depends, among other things, on its ability to convert a spin excitation into an electric charge signal, a phenomenon that requires a spin-orbit coupling (SOC). Here we report the observation of two effects that show the existence of SOC in large-area CVD grown single-layer graphene deposited on a single crystal film of the ferrimagnetic insulator yttrium iron garnet (YIG). The first is a magnetoresistance of graphene induced by the magnetic proximity effect with YIG. The second is the detection of a dc voltage along the graphene layer resulting from the conversion of the spin current generated by spin pumping from microwave driven ferromagnetic resonance into a charge current, which is attributed to the inverse Rashba-Edelstein effect.

Direct coupling between charge current and spin polarization by extrinsic mechanisms in graphene

“…This is especially true when the impurity-induced Rashba is large, as it may be the case of hydrogenated graphene 18,24 ; such an analysis will be presented elsewhere 47 . The present theory may also have important implications for understanding recent spin pumping experiments in CVD graphene involving the inverse of CISP 26 and the inverse of current-induced spin current 25,27 .…”

“…Although other groups have reproduced the nonlocal resistance measurements in adatom-decorated graphene, they have failed to observe the expected modulation with in-plane magnetic field (Hanle precession) 23,24 . Other recent experiments [25][26][27] have demonstrated spin-charge conversion in graphene by spin-pumping, and some 25,27 reported values of θ sH many orders of magnitude below what was obtained in earlier Hall-bar devices 18 . In our view, the confusing experimental situation calls for a more detailed theoretical analysis of how spin currents and charge currents are coupled by extrinsic SOC in graphene.…”

Quantum Hall effect in graphene with interface-induced spin-orbit coupling

“…Recently, there has been a significant progress in engineering those properties by proximity effect, which allows introducing spin-dependent features while preserving graphene's high electronic mobility. Graphene has been proximity-coupled with a magnetic thin layer of YIG for transport 17 and spin-pumping 18 measurements. SOC was also induced by proximity effect in graphene on top of different transition metal Dichalcogenites (TMDC) [19][20][21][22] and graphene decorated with Gold 23 .…”

Spin pumping into two-dimensional electron systems

“…Monatomic layers such as graphene and transition-metal dichalcogenides also have two-dimensional electronic structures [11][12][13][14][15] and are interesting candidates for spintronic applications [16][17][18]. For graphene high electronic mobilities of 3.5 × 10 5 cm 2 V −1 s −1 have been reported [19].…”