Local Sensing of Correlated Electrons in Dual-moiré Heterostructures using Dipolar Excitons

Li, Weijie; Devenica, Luka Matej; Zhang, Jin; Zhang, Yang; Lu, Xin; Watanabe, Kenji; Taniguchi, Takashi; Rubio, Ángel; Srivastava, Ajit

doi:10.48550/arxiv.2111.09440

Cited by 2 publications

(3 citation statements)

References 35 publications

(27 reference statements)

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“…We emphasize that the theoretical approach employed here in our study is robust, and provides quantitative microscopic insights into the spin-valley physics of these van der Waals heterobilayers. This framework can certainly be extended to more complex multilayered van der Waals heterostructures that also host dipolar excitons: for instance, large-angle twisted MoSe

/WSe

[ 126 , 127 ], homobilayers [ 22 , 125 ], trilayer hetero- and homo-structures [ 124 , 128 , 129 ], and MoSe

/WS

heterobilayers [ 99 , 130 , 131 ].…”

Section: Discussionmentioning

confidence: 99%

“…We emphasize that the theoretical approach employed here in our study is quite robust and provides quantitative microscopic insights into the spinvalley physics of these van der Waals heterobilayers. This framework can certainly be extended to more complex multilayered van der Waals heterostructures that also host dipolar excitons, for instance, large-angle twisted MoSe 2 /WS 2 126,127 , homobilayers 22,125 , trilayer hetero-and homo-structures 124,128,129 , and MoSe 2 /WS 2 heterobilayers 99,130,131 The DFT are performed using the WIEN2k code 81 , which implements a full potential all-electron scheme with augmented plane wave plus local orbitals (APW+lo) method. The crystal structures of monolayers and the heterostructure are generated using the atomic simulation environment (ASE) python package 132 .…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

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

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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.

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/WSe

[ 126 , 127 ], homobilayers [ 22 , 125 ], trilayer hetero- and homo-structures [ 124 , 128 , 129 ], and MoSe

/WS

heterobilayers [ 99 , 130 , 131 ].…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

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“…Recently, bilayer transition metal dichalcogenides (TMDs) have become a versatile platform to study the Hubbard model thanks to the coexistence of several intriguing features such as the reduction of electron hopping due to the formation of moiré lattice with large lattice constant, and the existence of both intra-and inter-layer excitons. These characteristics have enabled the realization of numerous effects of many-body physics such as metal-to-Mott insulator transition [4][5][6][7][8][9], generalized Wigner crystals [10][11][12][13][14], exciton-polaritons with moiré-induced nonlinearity [15], stripe phases [16], light-induced ferromagnetism [17]. Moreover, there have been recent exciting perspectives of exploring such effects in light-matter correlated systems [3,18,19].…”

Section: Introductionmentioning

confidence: 99%

Excitonic Mott insulator in a Bose-Fermi-Hubbard system of moiré WS2/WSe2 heterobilayer

Gao

Sarkar

Huang

et al. 2023

Preprint

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Understanding the Hubbard model is crucial for investigating various quantum many-body states and its fermionic and bosonic versions have been largely realized separately. Recently, transition metal dichalcogenides heterobilayers have emerged as a promising platform for simulating the rich physics of the Hubbard model. In this work, we explore the interplay between fermionic and bosonic populations, using a $\rm{WS}_2$/$\rm{WSe}_2$ heterobilayer device that hosts this hybrid particle density. We independently tune the fermionic and bosonic populations by electronic doping and optical injection of electron-hole pairs, respectively. This enables us to form strongly interacting excitons that are manifested in a large energy gap in the photoluminescence spectrum. The incompressibility of excitons is further corroborated by measuring exciton diffusion, which remains constant upon increasing pumping intensity, as opposed to the expected behavior of a weakly interacting gas of bosons, suggesting the formation of a bosonic Mott insulator. We explain our observations using a two-band model including phase space filling. Our system provides a controllable approach to the exploration of quantum many-body effects in the generalized Bose-Fermi-Hubbard model.

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Local Sensing of Correlated Electrons in Dual-moiré Heterostructures using Dipolar Excitons

Cited by 2 publications

References 35 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

Excitonic Mott insulator in a Bose-Fermi-Hubbard system of moiré WS2/WSe2 heterobilayer

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