Abstract
We investigate the transport properties of a graphene layer in the presence of Rashba spin-orbit interaction. Quite generally, spin-orbit interactions induce spin splittings and modifications of the graphene band structure. We calculate within the scattering approach the linear electric and thermoelectric responses of a clean sample when the Rashba coupling is localized around a finite region. We find that the thermoelectric conductance, unlike its electric counterpart, is quite sensitive to external modulations of the Fermi energy. Therefore, our results suggest that thermocurrent measurements may serve as a useful tool to detect nonhomogeneous spin-orbit interactions present in a graphene-based device. Furthermore, we find that the junction thermopower is largely dominated by an intrinsic term independently of the spin-orbit potential scattering. We discuss the possibility of canceling the intrinsic thermopower by resolving the Seebeck coefficient in the subband space. This causes unbalanced populations of electronic modes which can be tuned with external gate voltages or applied temperature biases.
Highlights
Graphene is a single layer of carbon atoms arranged on a two-dimensional honeycomb lattice [1,2]
The Rashba coupling strength can be externally tuned by modifying the electric field applied to a nearby gate [17]
The effect of nonhomogeneous Rashba couplings has been considered in the transport characteristics of two-dimensional systems [32,33,34,35,36]
Summary
Graphene is a single layer of carbon atoms arranged on a two-dimensional honeycomb lattice [1,2]. Recent works suggest large spin-orbit strengths in graphene layers under the influence of metallic substrates [7,8,9,10,11,12]. The Rashba coupling strength can be externally tuned by modifying the electric field applied to a nearby gate [17] This type of interaction leads to band splittings and enriched spintronic effects [18,19]. We investigate the influence of local Rashba spin-orbit interaction on the electric and thermoelectric properties of graphene. Since the Rashba coupling splits the graphene electronic band structure (see Fig. 1), the transmission depends on the subband index.
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