Tunable exciton valley-pseudospin orders in moiré superlattices

Excitons in two-dimensional (2D) semiconductors have offered an attractive platform for optoelectronic and valleytronic devices. Further realizations of correlated phases of excitons promise device concepts not possible in the single particle picture. Here we report tunable exciton “spin” orders in...

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Bibliographic Details
Published in:Nature communications 2024-05, Vol.15 (1), p.4254-4254, Article 4254
Main Authors: Xiong, Richen, Brantly, Samuel L., Su, Kaixiang, Nie, Jacob H., Zhang, Zihan, Banerjee, Rounak, Ruddick, Hayley, Watanabe, Kenji, Taniguchi, Takashi, Tongay, Seth Ariel, Xu, Cenke, Jin, Chenhao
Format: Article
Language:English
Subjects:
140/125
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639/925/357/1018
Bosons
Correlation
Electrons
Energy
Excitons
Fermions
Ferromagnetism
Helicity
Heterostructures
Humanities and Social Sciences
Light
Low dimensional semiconductors
Magnetic fields
multidisciplinary
Optoelectronic devices
Phase diagrams
Polarization
Polarization (spin alignment)
Science
Science & Technology - Other Topics
Science (multidisciplinary)
Spectrum analysis
Superlattices
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Summary:Excitons in two-dimensional (2D) semiconductors have offered an attractive platform for optoelectronic and valleytronic devices. Further realizations of correlated phases of excitons promise device concepts not possible in the single particle picture. Here we report tunable exciton “spin” orders in WSe 2 /WS 2 moiré superlattices. We find evidence of an in-plane ( xy ) order of exciton “spin”—here, valley pseudospin—around exciton filling v ex  = 1, which strongly suppresses the out-of-plane “spin” polarization. Upon increasing v ex or applying a small magnetic field of ~10 mT, it transitions into an out-of-plane ferromagnetic (FM -z ) spin order that spontaneously enhances the “spin” polarization, i.e., the circular helicity of emission light is higher than the excitation. The phase diagram is qualitatively captured by a spin-1/2 Bose–Hubbard model and is distinct from the fermion case. Our study paves the way for engineering exotic phases of matter from correlated spinor bosons, opening the door to a host of unconventional quantum devices. Control of correlated excitonic states is a key goal of modern optoelectronic physics. Here, the authors demonstrate filling- and field-tunable exciton valley-pseudospin orders in a moiré heterostructure.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-024-48725-z