The role of the Rashba coupling in spin-current of monolayer gapped graphene

Hasanirokh, Kobra; Azizi, J.; Phirouznia, A.; Mohammadpour, Hakimeh

doi:10.1140/epjb/e2014-40613-8

Cited by 6 publications

(4 citation statements)

References 33 publications

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“…17 Previous theoretical reports suggest a significant role of Rashba coupling in the generation of the spin current of vertical spins in monolayer graphene as the spin current can be increased by raising the Rashba coupling strength, while the sign of the spin current is controllable by the direction of the external bias voltage driving the current. 18 Then, for an infinite graphene with uniform Rashba SOC, the equilibrium spin current is proportional to α 2 , where α is the Rashba strength. 19 Hence, spin current in the spin-FET can be tuned or manipulated by varying the Rashba SOC parameter.…”

Section: Introductionmentioning

confidence: 99%

“…The previous experiments have demonstrated that the strength of the Rashba field and spin precession rate can be controlled by the gate voltage. ,, The first spintronic device concept that utilized Rashba SOC was a spin field-effect transistor . Previous theoretical reports suggest a significant role of Rashba coupling in the generation of the spin current of vertical spins in monolayer graphene as the spin current can be increased by raising the Rashba coupling strength, while the sign of the spin current is controllable by the direction of the external bias voltage driving the current . Then, for an infinite graphene with uniform Rashba SOC, the equilibrium spin current is proportional to α 2 , where α is the Rashba strength .…”

Section: Introductionmentioning

confidence: 99%

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Spin-Current Modulation in Hexagonal Buckled ZnTe and CdTe Monolayers for Self-Powered Flexible-Piezo-Spintronic Devices

Mohanta¹,

IS²,

Kishore³

et al. 2021

ACS Appl. Mater. Interfaces

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The next-generation spintronic device demands the gated control of spin transport across the semiconducting channel through the replacement of the external gate voltage source by the piezo potential, as experimentally demonstrated in Zhu et al. ACS Nano, 2018, 12 (2), 1811−1820. Consequently, a high level of out-of-plane piezoelectricity together with a large Rashba spin splitting is sought after in semiconducting channel materials. Inspired by this experiment, a new hexagonal buckled two-dimensional (2D) semiconductor, ZnTe, and its iso-electronic partner, CdTe, are proposed herewith. These 2D materials show a strong spin-orbit coupling (SOC), which is evidenced by a large Rashba constant of 1.06 and 1.27 eV•Å, respectively, in ZnTe and CdTe monolayers. Moreover, these Rashba semiconductors exhibit a giant out-of-plane piezoelectric coefficient (d 33 ) = 88.68 and 172.61 pm/V, and can thereby generate a high piezo potential for gating purposes in spin field-effect transistors (spin-FETs). While the low elastic stiffness implies the mechanical flexibility or stretchability in these monolayers. The Rashba constants are found to be effectively modulated via external perturbations, such as strain and electric field. The wide band gap provides ample room for modulation in its electronic properties via external perturbations. Such scope is severely limited in previously reported narrow band gap Rashba semiconductors. The fascinating results found in this work indicate their great potential for applications in next-generation self-powered flexible-piezo-spintronic devices. Moreover, a new class of hexagonal buckled ZnX (X: S, Se, or Te) monolayers is proposed herein based on their previously synthesized bulk counterparts, while their electronic, mechanical, piezoelectric, and thermal properties have been thoroughly investigated using the state-of-art density functional theory (DFT).

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spin-Current Modulation in Hexagonal Buckled ZnTe and CdTe Monolayers for Self-Powered Flexible-Piezo-Spintronic Devices

Mohanta¹,

IS²,

Kishore³

et al. 2021

ACS Appl. Mater. Interfaces

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show abstract

“…The extrinsic or Rashba SOC, however, results from the lack of inversion symmetry due to perpendicular electric fields, substrate effects, chemical doping, or curvature of graphene corrugations and can be responsible for inducing a spin polarization in graphene. [9,10] The influences of intrinsic and Rashba SOCs on the transport properties of graphene monolayer systems have extensively been studied in the recent years [5,6,[11][12][13][14]. For instance, it was shown that spin polarization induced by a charge current can reside in the graphene plane and perpendicular to the electric field while its sign changes by varying the Fermi level through an external gate voltage [11].…”

mentioning

confidence: 99%

“…Spintronics is an emerging field which has aimed at exploiting the spin degree of freedom to construct faster and high-performance low-power nanoscale devices [1]. The discovery of isolated graphene monolayer [2,3], a single layer of carbon atoms, with unique electrical, optical and thermal properties has triggered numerous efforts to achieve graphene-based nanoscale devices [4][5][6][7]. The massless Dirac fermions in ballistic graphene can reflect chirality and linear dispersion relation of graphene around the Dirac points, two inequivalent corners of the first Brillouin zone [8].…”

mentioning

confidence: 99%

Strain-controlled spin and charge pumping in graphene devices via spin-orbit coupled barriers

Mohammadkhani¹,

Abdollahipour²,

Alidoust³

2015

EPL

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-We theoretically propose a graphene-based adiabatic quantum pump with intrinsic spin-orbit coupling (SOC) subject to strain where two time-dependent extrinsic spin-orbit coupled barriers drive spin and charge currents. We study three differing operation modes where i) location, ii) chemical potential, and iii) SOC of the two barriers oscillate periodically and out of phase around their equilibrium states. Our results demonstrate that the amplitude of adiabatically pumped currents highly depends on the considered operation mode. We find that such a device operates with highest efficiency and in a broader range of parameters where the barriers' chemical potential drives the quantum pump. Our results also reveal that by introducing strain to the system, one can suppress or enhance the charge and spin currents separately, depending on strain direction.Spintronics is an emerging filed which has aimed at exploiting the spin degree of freedom to construct faster and high performance low-power nanoscale devices [1]. The discovery of isolated graphene monolayer [2,3], a single layer of Carbon atoms, with unique electrical, optical and thermal properties has triggered numerous efforts to achieve graphene-based nanoscale devices [5][6][7][8]. The massless Dirac fermions in ballistic graphene can reflect chirality and linear dispersion relation of graphene around the Dirac points; two inequivalent corners of the first Brillouin zone [4]. Also, the long spin relaxation time of the Dirac fermions in graphene monolayers due to a small intrinsic spin-orbit coupling (SOC) which originates from the intra-atomic spin-orbit coupling of the Carbon atoms has made it an exceptional candidate to the spintronics devices [7].Quite recently, it was experimentally demonstrated that a strong Rashba SOC ∼ 17 meV can be induced into graphene monolayers by means of proximity to a semiconducting tungsten disulphide substrate [8]. This finding is highly appealing in terms of generation and manipulation of spin currents in more controllable platforms. The intrinsic SOC that can be caused by the crystalline potential associated with the band structure respects all the lattice symmetries in graphene and results in a small energy gap at the Dirac points. The extrinsic or Rashba SOC, however, results from the lack of inversion symmetry due to perpendicular electric fields, substrate effects, chemical doping, or curvature of graphene corrugations and can be responsible for inducing a spin polarization in graphene. [9,10] The influences of intrinsic and Rashba SOCs on the transport properties of graphene monolayer systems have extensively been studied in the recent years [5,6,[11][12][13][14]. For instance, it was shown that spin polarization induced by a charge current can reside in the graphene plane and perpendicular to the electric field while its sign changes by varying the Fermi level through an external gate voltage [11]. Also, it was theoretically found that the interplay of massive electrons with SOC or strain in a graphene layer can...

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Spin-current and pseudo-spin density response functions in graphene

Phirouznia

2020

Superlattices and Microstructures

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The role of the Rashba coupling in spin-current of monolayer gapped graphene

Cited by 6 publications

References 33 publications

Spin-Current Modulation in Hexagonal Buckled ZnTe and CdTe Monolayers for Self-Powered Flexible-Piezo-Spintronic Devices

Spin-Current Modulation in Hexagonal Buckled ZnTe and CdTe Monolayers for Self-Powered Flexible-Piezo-Spintronic Devices

Strain-controlled spin and charge pumping in graphene devices via spin-orbit coupled barriers

Spin-current and pseudo-spin density response functions in graphene

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