Tailoring emergent spin phenomena in Dirac material heterostructures

Khokhriakov, Dmitrii; Cummings, Aron W.; Song, Kenan; Vila, Marc; Karpiak, Bogdan; Dankert, André; Roche, Stephan; Dash, Saroj P.

doi:10.1126/sciadv.aat9349

Cited by 74 publications

(63 citation statements)

References 53 publications

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“…Since each QL is about 1 nm in thickness, these materials are in between the 2D and 3D regime, depending on how many QLs one investigates. Nevertheless, they are important for practical applications 34 , due to their topologically protected 35,36 and well conducting surface states 37 , and for proximity induced phenomena [38][39][40][41] , since strong SOC is present. When the topological insulators act as a substrate, the 2D regime (1-2 QLs) is sufficient, as proximity effects are of short range nature.…”

Section: Introductionmentioning

confidence: 99%

Single and bilayer graphene on the topological insulator Bi2Se3 : Electronic and spin-orbit properties from first principles

Zollner

Fabian

2019

Phys. Rev. B

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We present a detailed study of the electronic and spin-orbit properties of single and bilayer graphene in proximity to the topological insulator Bi2Se3. Our approach is based on first-principles calculations, combined with symmetry derived model Hamiltonians that capture the low-energy band properties. We consider single and bilayer graphene on 1-3 quintuple layers of Bi2Se3 and extract orbital and proximity induced spin-orbit coupling (SOC) parameters. We find that graphene gets significantly hole doped (350 meV), but the linear dispersion is preserved. The proximity induced SOC parameters are about 1 meV in magnitude, and are of valley-Zeeman type. The induced SOC depends weakly on the number of quintuple layers of Bi2Se3. We also study the effect of a transverse electric field, that is applied across heterostructures of single and bilayer graphene above 1 quintuple layer of Bi2Se3. Our results show that band offsets, as well as proximity induced SOC parameters can be tuned by the field. Most interesting is the case of bilayer graphene, in which the band gap, originating from the intrinsic dipole of the heterostructure, can be closed and reopened again, with inverted band character. The switching of the strong proximity SOC from the conduction to the valence band realizes a spin-orbit valve. Additonally, we find a giant increase of the proximity induced SOC of about 200%, when we decrease the interlayer distance between graphene and Bi2Se3 by only 10%. Finally, for a different substrate material Bi2Te2Se, band offsets are significantly different, with the graphene Dirac point located at the Fermi level, while the induced SOC strength stays similar in magnitude compared to the Bi2Se3 substrate.

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Section: Introductionmentioning

confidence: 99%

Single and bilayer graphene on the topological insulator Bi2Se3 : Electronic and spin-orbit properties from first principles

Zollner

Fabian

2019

Phys. Rev. B

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“…The original motivation for studying the properties of a graphene layer coupled to the 2D surface of a 3DTI was the possibility of inducing strong SOC or novel spin textures in the graphene layer predicted by theoretical models . Excitingly, this proximity‐induced SOC has recently been observed using a combination of transport measurements and ab initio calculations . Additionally, we also note that the possibility of inducing Dirac states with very low Fermi velocity, in which interaction effects could be greatly enhanced, has also been discussed.…”

Section: Graphene‐ti Heterostructuresmentioning

confidence: 80%

“…[14,53,54] Excitingly, this proximity-induced SOC has recently been observed using a combination of transport measurements and ab initio calculations. [15] Additionally, we also note that the possibility of inducing Dirac states with very low Fermi velocity, in which interaction effects could be greatly enhanced, [55] has also been discussed.…”

Section: Graphene-ti Heterostructuresmentioning

confidence: 97%

“…For example, graphene possesses only very weak SOC but has very high electron mobility at room temperature. By combining graphene with the 2D surface of a 3D topological insulator (TI), the SOC in the graphene layer can be enhanced by an order of magnitude . Additionally, as we discuss in Section 5.1, vdW heterostructures with SOC appear to be ideal systems for realizing unconventional odd‐frequency superconducting states .…”

Section: Introductionmentioning

confidence: 99%

“…By combining graphene with the 2D surface of a 3D topological insulator (TI), [11][12][13] the SOC in the graphene layer can be enhanced by an order of magnitude. [14,15] Additionally, as we discuss in Section 5.1, vdW heterostructures with SOC appear to be ideal systems for realizing unconventional odd-frequency superconducting states. [16] In contrast to conventional superconducting states, the defining feature of odd-frequency superconductors is that they host Cooper pairs which are odd functions in the relative time, making these states intrinsically dynamical.The literature on vdW systems is by now very large, for this reason we restrict ourselves to a particular subset of vdW systems that are among the most relevant to the subject of this special issue and that we have studied over the past few years.…”

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confidence: 99%

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Van Der Waals Heterostructures with Spin‐Orbit Coupling

Rossi

Triola

2019

Annalen der Physik

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Herein, recent work on van der Waals (vdW) systems in which at least one of the components has strong spin‐orbit coupling is reviewed, focussing on a selection of vdW heterostructures to exemplify the type of interesting electronic properties that can arise in these systems. First a general effective model to describe the low energy electronic degrees of freedom in these systems is presented. The model is then applied to study the case of (vdW) systems formed by a graphene sheet and a topological insulator. The electronic transport properties of such systems are discussed and it is shown how they exhibit much stronger spin‐dependent transport effects than isolated topological insulators. Then, vdW systems are considered in which the layer with strong spin‐orbit coupling is a monolayer transition metal dichalcogenide (TMD) and graphene‐TMD systems are briefly discussed. In the second part of the article, a case is discussed in which the vdW system includes a superconducting layer in addition to the layer with strong spin‐orbit coupling. It is shown in detail how these systems can be designed to realize odd‐frequency superconducting pair correlations. Finally, twisted graphene‐NbSe2 bilayer systems are discussed as an example in which the strength of the proximity‐induced superconducting pairing in the normal layer, and its Ising character, can be tuned via the relative twist angle between the two layers forming the heterostructure.

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2D Polarized Materials: Ferromagnetic, Ferrovalley, Ferroelectric Materials, and Related Heterostructures

Chu

Wang

et al. 2020

Advanced Materials

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The emergence of 2D polarized materials, including ferromagnetic, ferrovalley, and ferroelectric materials, has demonstrated unique quantum behaviors at atomic scales. These polarization behaviors are tightly bonded to the new degrees of freedom (DOFs) for next generation information storage and processing, which have been dramatically developed in the past few years. Here, the basic 2D polarized materials system and related devices’ application in spintronics, valleytronics, and electronics are reviewed. Specifically, the underlying physical mechanism accompanied with symmetry broken theory and the modulation process through heterostructure engineering are highlighted. These summarized works focusing on the 2D polarization would continue to enrich the cognition of 2D quantum system and promising practical applications.

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Tailoring emergent spin phenomena in Dirac material heterostructures

Abstract: Dirac material–based heterostructures reveal enhanced spin-orbit coupling with an emerging spin texture.

Cited by 74 publications

References 53 publications

Single and bilayer graphene on the topological insulator Bi2Se3 : Electronic and spin-orbit properties from first principles

Single and bilayer graphene on the topological insulator Bi2Se3 : Electronic and spin-orbit properties from first principles

Van Der Waals Heterostructures with Spin‐Orbit Coupling

2D Polarized Materials: Ferromagnetic, Ferrovalley, Ferroelectric Materials, and Related Heterostructures

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