Strain-induced chiral symmetry breaking leads to large Dirac cone splitting in graphene/graphane heterostructure

Das, Deya; Bhattacharyya, Swastibrata; Muñoz, Enrique; Singh, Abhishek K.

doi:10.1103/physrevb.94.115438

Cited by 18 publications

(7 citation statements)

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“…Many chemical reactions with graphene are reversible; in particular, hydrogenation of Gr is thermally, chemically, and mechanically reversible. − While this property can be beneficial, for example, enabling patterning of electrically conductive regions of graphene in an insulating and n-doping hydrogenated graphene matrix, the reversion of hydrogenated graphene to pristine graphene raises the question of how best to stabilize devices made from these materials for the long-term. Indeed, worries over the stability of hydrogenated graphene were highlighted by Geim and Grigorieva, who stated, “Graphane (fully hydrogenated graphene) gradually loses its hydrogen and is unlikely to be useful for making heterostructures,” despite its shown promise in spintronics, in transferring ferromagnetism, and in strain-induced band gap formation . Thus, finding a way to chemically stabilize hydrogenated graphene represents a critical step in enabling practical use of this unique material in heterostructure devices.…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, worries over the stability of hydrogenated graphene were highlighted by Geim and Grigorieva, who stated, "Graphane (fully hydrogenated graphene) gradually loses its hydrogen and is unlikely to be useful for making heterostructures," 10 despite its shown promise in spintronics, 11 in transferring ferromagnetism, 12 and in strain-induced band gap formation. 13 Thus, finding a way to chemically stabilize hydrogenated graphene represents a critical step in enabling practical use of this unique material in heterostructure devices.…”

Section: ■ Introductionmentioning

confidence: 99%

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Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

2017

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We show that dehydrogenation of hydrogenated graphene proceeds much more slowly for bilayer systems than for single layer systems. We observe that an underlayer of either pristine or hydrogenated graphene will protect an overlayer of hydrogenated graphene against a number of chemical oxidants, thermal dehydrogenation, and degradation in an ambient environment over extended periods of time. Chemical protection depends on the ease of oxidant intercalation, with good intercalants such as Br demonstrating much higher reactivity than poor intercalants such as 1,2-dichloro-4,5-dicyanonbenzoquinone (DDQ). Additionally, the rate of dehydrogenation of hydrogenated graphene at 300 °C in H/Ar was reduced by a factor of roughly 10 in the presence of a protective underlayer of graphene or hydrogenated graphene. Finally, the slow dehydrogenation of hydrogenated graphene in air at room temperature, which is normally apparent after a week, could be completely eliminated in samples with protective underlayers over the course of 39 days. Such protection will be critical for ensuring the long-term stability of devices made from functionalized graphene.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

2017

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“…61 The Dirac cone further splits into π z1 , π z2 (π z1′ , π z2′ ) for its spin-up and spin-down states, respectively, as shown in the inset of Figure 2(a). The hybridization of graphene with the spin-up states of CrI 3 along with the lattice strain considered (the constraint of considering MoS 2 in the trilayer results in this additional strain on graphene) 62 breaks the symmetry at the Dirac cone and induces a band split of ∼0.47 eV corresponding to π z1 -π z2 orbitals of graphene as seen in the inset of Figure 2(a). For the spin-down case, the Dirac cone of graphene lies within the spin-down bandgap of CrI 3 and only a strain-induced band split of ∼0.08 eV is observed for π z1′ -π z2′ states.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Effect of Magnetic Tuning and Induced Charge Transfer Isotropy in a CrI₃-Based 2D Trilayer Heterostructure

Chakraborty

Ravikumar

2022

J. Phys. Chem. C

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We predict the induction/suppression of Chern insulating states in graphene and semiconductor to metal phase transition in MoS 2 under the influence of magnetic tuning of CrI 3 from a ferromagnetic (FM) case to an antiferromagnetic (AFM) one. We examine the spin-dependent electronic structure of the trilayer constructed with a 2D magnetic insulator (CrI 3 ) sandwiched between graphene and MoS 2 using first principle calculations. We observe that the induced σ z lattice strain breaks the symmetry of graphene's Dirac cone (which shows a bandgap of ∼0.47 eV), and the interlayer charge transfer results in a metallic trilayer. In the ferromagnetic case, for the spin-down channel, the Dirac cone split lies in the bandgap of CrI 3 , inducing Chern insulating states of graphene. As we switch to an antiferromagnetic case, graphene loses its Chern insulating states and hybridizes with the substrate in both of the spin channels. When spin−orbit coupling interactions are considered, the Dirac cone split of graphene is preserved which now lies in the bandgap of CrI 3 , enhancing its Chern insulating properties. Hexagonal MoS 2 however shows a semiconductor to metal transition in both the FM and the AFM cases which we believe has not been reported previously. Under the effect of spin− orbit coupling, the valence bands of MoS 2 shift above the Fermi level, retaining the semiconductor to metal transition. The effects examined in this work could lead to the design of CrI 3 -based 2D MOS-like devices with potential applications in ultrathin supercapacitors and quantum transistors.

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“…So far, bandgap opening has been achieved in the heterostructures of graphene with h-BN, 15,16 SiC, 17,18 h-C 3 N 4 , 19 CH, 20 and g-GeC. 21 Oftentimes, this bandgap opening has been attributed to the sublattice symmetry breaking.…”

Section: ■ Introductionmentioning

confidence: 99%

“…So far, bandgap opening has been achieved in the heterostructures of graphene with h-BN, , SiC, , h-C 3 N 4 , CH, and g-GeC . Oftentimes, this bandgap opening has been attributed to the sublattice symmetry breaking. ,,, Interestingly, in several heterostructures like graphene/MoS 2 (gr/MoS 2 ), graphene/SnS 2 (gr/SnS 2 ), or graphene/phosphorene (gr/phos), in spite of a sublattice symmetry breaking the Dirac cone does not split. On the other hand, there are heterostructures where even after Dirac cone splitting, the system remains metallic.…”

Section: Introductionmentioning

confidence: 99%

Critical Sublattice Symmetry Breaking: A Universal Criterion for Dirac Cone Splitting

et al. 2019

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In this section, we present a theory for Dirac cone splitting in graphene van der Waals heterostructures, where the substrate may induce chiral symmetry breaking. Our model is based on a tight-binding representation of single-layer graphene, subjected to an on-site potential representing the proximity of the substrate atoms. The fact that this local potential may differ at each site, provides a mechanism for chiral symmetry breaking and the corresponding splitting of the Dirac cone in graphene. From an effective tight-binding model for the graphene-heterostructure, a simple stoichiometric rule is obtained to predict the conditions for Dirac cone splitting in the energy spectrum.

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Strain-induced chiral symmetry breaking leads to large Dirac cone splitting in graphene/graphane heterostructure

Cited by 18 publications

References 55 publications

Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

Effect of Magnetic Tuning and Induced Charge Transfer Isotropy in a CrI₃-Based 2D Trilayer Heterostructure

Critical Sublattice Symmetry Breaking: A Universal Criterion for Dirac Cone Splitting

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Strain-induced chiral symmetry breaking leads to large Dirac cone splitting in graphene/graphane heterostructure

Cited by 18 publications

References 55 publications

Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

Protection from Below: Stabilizing Hydrogenated Graphene Using Graphene Underlayers

Effect of Magnetic Tuning and Induced Charge Transfer Isotropy in a CrI3-Based 2D Trilayer Heterostructure

Critical Sublattice Symmetry Breaking: A Universal Criterion for Dirac Cone Splitting

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Effect of Magnetic Tuning and Induced Charge Transfer Isotropy in a CrI₃-Based 2D Trilayer Heterostructure