Proximity-enhanced valley Zeeman splitting at the WS$_2$/graphene interface

Junior, Paulo E. Faria; Naimer, Thomas; McCreary, Kathleen M.; Jonker, B. T.; Finley, Jonathan J.; Crooker, S. A.; Fabian, Jaroslav; Stier, Andreas V.

doi:10.48550/arxiv.2301.12234

Cited by 1 publication

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the heterostructure bands at the K point, c W(Mo)± , v W(Mo) and v ± , we observe the typical sign changes from R to H stackings because of the opposite K/K (0 • twist) and K/-K (60 • twist) alignment 20,64 . For the conduction bands, we observe deviations of L z on the order of ≤ 0.05 when compared to the monolayer case, consistent with a higher localization of conduction bands 27 . We therefore would expect larger changes arising in the valence bands, which is indeed the case, partic-ularly for the v ± bands, and for the v W and v Mo bands of the H h h stacking.…”

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...supporting

confidence: 58%

“…We note that, in order to properly evaluate the intralayer exciton physics, it would be desirable to go beyond DFT calculations and employ the GW + Bethe-Salpeter formalism 45,65,97,125 , which is beyond the scope of this work. Nonetheless, since these intralayer excitons are also quite localized in k-space 10,14,27 , the spin and orbital angular momenta of the Bloch bands should account for the majority of the hybridization effects.…”

Section: Discussionmentioning

confidence: 99%

“…1g) at zero electric field and at the equilibrium interlayer distance. We follow the recent firstprinciples developments to compute the orbital angular momenta in monolayer TMDCs [64][65][66][67] , which has also been successfully applied to investigate a variety of more complex TMDC-based systems and van der Waals heterostructures 27,53,57,80,85,[92][93][94][95][96][97][98][99] . We do not aim to provide a detailed description of the methodology here, but briefly summarize the main points.…”

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...mentioning

confidence: 99%

“…53,57,64,67,80 but here we extend our analysis to incorporate more bands and later investigate the dependence of electric field and interlayer distance. We emphasize here that the electronic and spin properties calculated with the DFT also provide a reliable benchmark to further studies since WIEN2k 81 is one of the most accurate DFT codes available 100 ) and particularly suitable to study spin-physics of 2D materials and van der Waals heterostructures 23,24,27,95,[101][102][103][104][105] .…”

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...mentioning

confidence: 99%

“…Furthermore, the van der Waals nature of TMDC materials facilitates the vertical stacking and integration of different layers, the key ingredient driving the burgeoning research field of van der Waals heterostructures [15][16][17][18] . These novel heterostructures offer a fantastic playground to investigate emergent physical phenomena and effects of proximity interaction, certainly not limited to TMDCs [19][20][21][22] but also encompassing other attractive materials, such as graphene 13,[23][24][25][26][27] , boron nitride [28][29][30] , ferromagnetic CrX 3 (X=I,Br) [31][32][33][34][35] and many others.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Signatures of Electric Field and Layer Separation Effects on the Spin-Valley Physics of MoSe2/WSe2 Heterobilayers: From Energy Bands to Dipolar Excitons

Faria

Fabian

2023

Nanomaterials

View full text Add to dashboard Cite

Multilayered van der Waals heterostructures based on transition metal dichalcogenides are suitable platforms on which to study interlayer (dipolar) excitons, in which electrons and holes are localized in different layers. Interestingly, these excitonic complexes exhibit pronounced valley Zeeman signatures, but how their spin-valley physics can be further altered due to external parameters—such as electric field and interlayer separation—remains largely unexplored. Here, we perform a systematic analysis of the spin-valley physics in MoSe2/WSe2 heterobilayers under the influence of an external electric field and changes of the interlayer separation. In particular, we analyze the spin (Sz) and orbital (Lz) degrees of freedom, and the symmetry properties of the relevant band edges (at K, Q, and Γ points) of high-symmetry stackings at 0° (R-type) and 60° (H-type) angles—the important building blocks present in moiré or atomically reconstructed structures. We reveal distinct hybridization signatures on the spin and the orbital degrees of freedom of low-energy bands, due to the wave function mixing between the layers, which are stacking-dependent, and can be further modified by electric field and interlayer distance variation. We find that H-type stackings favor large changes in the g-factors as a function of the electric field, e.g., from −5 to 3 in the valence bands of the Hhh stacking, because of the opposite orientation of Sz and Lz of the individual monolayers. For the low-energy dipolar excitons (direct and indirect in k-space), we quantify the electric dipole moments and polarizabilities, reflecting the layer delocalization of the constituent bands. Furthermore, our results show that direct dipolar excitons carry a robust valley Zeeman effect nearly independent of the electric field, but tunable by the interlayer distance, which can be rendered experimentally accessible via applied external pressure. For the momentum-indirect dipolar excitons, our symmetry analysis indicates that phonon-mediated optical processes can easily take place. In particular, for the indirect excitons with conduction bands at the Q point for H-type stackings, we find marked variations of the valley Zeeman (∼4) as a function of the electric field, which notably stands out from the other dipolar exciton species. Our analysis suggests that stronger signatures of the coupled spin-valley physics are favored in H-type stackings, which can be experimentally investigated in samples with twist angle close to 60°. In summary, our study provides fundamental microscopic insights into the spin-valley physics of van der Waals heterostructures, which are relevant to understanding the valley Zeeman splitting of dipolar excitonic complexes, and also intralayer excitons.

show abstract

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...supporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...mentioning

confidence: 99%

Section: Spin-valley Physics At the Band Edges A Pristine Heterostruc...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Signatures of Electric Field and Layer Separation Effects on the Spin-Valley Physics of MoSe2/WSe2 Heterobilayers: From Energy Bands to Dipolar Excitons

Faria

Fabian

2023

Nanomaterials

View full text Add to dashboard Cite

show abstract

Proximity-enhanced valley Zeeman splitting at the WS$_2$/graphene interface

Cited by 1 publication

References 0 publications

Signatures of Electric Field and Layer Separation Effects on the Spin-Valley Physics of MoSe2/WSe2 Heterobilayers: From Energy Bands to Dipolar Excitons

Signatures of Electric Field and Layer Separation Effects on the Spin-Valley Physics of MoSe2/WSe2 Heterobilayers: From Energy Bands to Dipolar Excitons

Contact Info

Product

Resources

About