Signatures of Wigner crystal of electrons in a monolayer semiconductor

Smoleński, T.; Dolgirev, Pavel E.; Kuhlenkamp, Clemens; Popert, Alexander; Shimazaki, Yuya; Back, Patrick; Lu, Xiaobo; Kroner, Martin; Watanabe, Kenji; Taniguchi, Takashi; Esterlis, Ilya; Demler, Eugene; İmamoğlu, Ataç

doi:10.1038/s41586-021-03590-4

Cited by 158 publications

(108 citation statements)

References 54 publications

Supporting

Mentioning

101

Contrasting

Unclassified

Order By: Relevance

“…In particular, we presented a microscopic mechanism for the formation of the nematic-II state via π/3 intersections between columnar fragments. As a subject of future work, it would be interesting to study the implications of our findings for the melting of WCs without a lattice potential, such as those recently observed in [24,25].…”

mentioning

confidence: 85%

Melting of generalized Wigner crystals in transition metal dichalcogenide heterobilayer Moiré systems

Matty¹,

Kim²

2021

Preprint

View full text Add to dashboard Cite

Moiré superlattice systems such as transition metal dichalcogenide heterobilayers have garnered significant recent interest due to their promising utility as tunable solid state simulators. Recent experiments on a WSe2/WS2 heterobilayer detected incompressible charge ordered states that one can view as generalized Wigner crystals. The tunability of the hetero-TMD Moiré system presents an opportunity to study the rich set of possible phases upon melting these charge-ordered states.Here we use Monte Carlo simulations to study these intermediate phases in between incompressible charge-ordered states in the strong coupling limit. We find two distinct stripe solid states to be each preceded by distinct types of nematic states. In particular, we discover microscopic mechanisms that stabilize each of the nematic states, whose order parameter transforms as the two-dimensional E representation of the Moiré lattice point group. Our results provide a testable experimental prediction of where both types of nematic occur, and elucidate the microscopic mechanism driving their formation.

show abstract

mentioning

confidence: 85%

Melting of generalized Wigner crystals in transition metal dichalcogenide heterobilayer Moiré systems

Matty¹,

Kim²

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…with ∆ = gµ B |B G |/2 and |B G | the amplitude of the first Fourier component of the periodic magnetic field. We set J = 300 meV and m X = 1.3 m e , motivated by the values estimated for MoSe 2 monolayers, and fix the lattice constant of the periodic magnetic field to a = 10 nm [22].…”

Section: Vicinity Of the K And K' Valleys Readsmentioning

confidence: 99%

“…Next to the band structure, we depict the zero momentum spectral functions A(E) for the σ − and σ + subspaces which are directly accessible via optical spectroscopy. In contrast to non-magnetic potentials, the Umklapp resonances at the Γ-point exhibit a pronounced splitting [10,22]. The emergence of additional peaks in the exciton spectrum serves as a direct signature of periodic magnetic structures, while their splitting distinguishes them from a purely electronic periodic potential.…”

Section: Vicinity Of the K And K' Valleys Readsmentioning

confidence: 99%

“…We find that the brightest Umklapp peaks, which originate from Bragg scattering of transversely polarised excitons, have a relative oscillator strength of 1 % for ∆ = 1.5 meV (|B G | 12 T). Provided that the exciton linewidth is predominantly due to radiative decay, this splitting can be easily observed [10,22]. This detection scheme for periodic magnetization is suitable to detect modulations with small moiré lattice constants of 5-20 nm, which are inaccessible to established imagining techniques such as NV magnetometry [23] [24].…”

Section: Vicinity Of the K And K' Valleys Readsmentioning

confidence: 99%

“…Umklapp signatures of a ferromagnetic triangular lattice.-Recent experiments have demonstrated the possibility to generate periodic charge distributions at low car-rier density such as Wigner crystals in TMD monolayers [22,25] and Mott-Wigner states in twisted bilayers [10,26,27]. The emergence of excitonic Umklapp resonances in optical spectroscopy due to exciton-electron interactions has served as a direct probe of broken translational invariance of electrons [10,22]. In TMDs, excitons and electrons interact differently depending on whether they are in the same or opposite valley [28].…”

Section: Vicinity Of the K And K' Valleys Readsmentioning

confidence: 99%

See 2 more Smart Citations

Optical signatures of periodic magnetization: the moiré Zeeman effect

Salvador,

Kuhlenkamp,

Ciorciaro

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Detecting magnetic order at the nanoscale is of central interest for the study of quantum magnetism in general, and the emerging field of moiré magnets in particular. Here, we analyze the exciton band structure that arises from a periodic modulation of the valley Zeeman effect. Despite long-range electron-hole exchange interactions, we find a sizable splitting in the energy of the bright circularly-polarized exciton Umklapp resonances, which serves as a direct optical probe of magnetic order. We first analyze quantum moiré magnets realized by periodic ordering of electron spins in Mott-Wigner states of transition metal dichalcogenide (TMD) monolayers or twisted bilayers: we show that spin-valley dependent exciton-electron interactions allow for probing the spin-valley order of electrons and demonstrate that it is possible to observe unique signatures of ferromagnetic order in a triangular lattice and both ferromagnetic and Néel order in a honeycomb lattice. We then focus on semiclassical moiré magnets realized in twisted bilayers of ferromagnetic materials: we propose a detection scheme for moiré magnetism which is based on inter-layer exchange coupling between spins in a moiré magnet and excitons in a TMD monolayer.

show abstract

Through the Lens of a Momentum Microscope: Viewing Light‐Induced Quantum Phenomena in 2D Materials

2022

View full text Add to dashboard Cite

Van der Waals (vdW) materials at their two-dimensional limit are diverse, flexible, and unique laboratories to study fundamental quantum phenomena and their future applications. Their novel properties rely on their pronounced Coulomb interactions, variety of crystal symmetries and spinphysics, and the ease of incorporation of different vdW materials to form sophisticated heterostructures. In particular, the excited state properties of many two-dimensional semiconductors and semi-metals are relevant for their technological applications, particularly those that can be induced by light. In this paper, we review the recent advances made in studying out-of-equilibrium, light-induced, phenomena in these materials using powerful, surface-sensitive, time-resolved photoemission-based techniques, with a particular emphasis on the emerging multi-dimensional photoemission spectroscopy technique of time-resolved momentum microscopy. We discuss the advances this technique has enabled in studying the nature and dynamics of occupied excited states in these materials. Then, we project for the future research directions opened by these scientific and instrumental advancements, studying the physics of two-dimensional materials and the opportunities to engineer their band-structure and band-topology by laser fields.

show abstract

Signatures of Wigner crystal of electrons in a monolayer semiconductor

Cited by 158 publications

References 54 publications

Melting of generalized Wigner crystals in transition metal dichalcogenide heterobilayer Moiré systems

Melting of generalized Wigner crystals in transition metal dichalcogenide heterobilayer Moiré systems

Optical signatures of periodic magnetization: the moiré Zeeman effect

Through the Lens of a Momentum Microscope: Viewing Light‐Induced Quantum Phenomena in 2D Materials

Contact Info

Product

Resources

About