Charge transfer excitations, pair density waves, and superconductivity in moiré materials
Name
PhysRevB.102.235423.pdf
Description
Published version
Size
907.64 KB
Format
Adobe PDF
Checksum (MD5)
0e6ce39e8187c2da515503a306377593
Author(s)
Slagle, Kevin
Fu, Liang
Date Issued
2020
Journal
Physical Review B
Publisher
American Physical Society (APS)
Citation
Slagle, Kevin and Fu, Liang. 2020. "Charge transfer excitations, pair density waves, and superconductivity in moiré materials." Physical Review B, 102 (23).
Version
Final published version
Abstract
© 2020 American Physical Society. Transition-metal dichalcogenide (TMD) bilayers are a new class of tunable moiré systems attracting interest as quantum simulators of strongly interacting electrons in two dimensions. In particular, recent theory predicts that the correlated insulator observed in WSe2/WS2 at half filling is a charge-transfer insulator similar to cuprates and, upon further hole doping, exhibits a transfer of charge from anionlike to cationlike orbitals at different locations in the moiré unit cell. In this work, we demonstrate that in this doped charge-transfer insulator, tightly bound charge-2e excitations can form to lower the total electrostatic repulsion. This composite excitation, which we dub a trimer, consists of a pair of holes bound to a charge-transfer exciton. When the bandwidth of doped holes is small, trimers crystallize into insulating pair density waves at a sequence of commensurate doping levels. When the bandwidth becomes comparable to the pair binding energy, itinerant holes and charge-2e trimers interact resonantly, leading to unconventional superconductivity similar to superfluidity in an ultracold Fermi gas near Feshbach resonance. Our theory is broadly applicable to strongly interacting charge-transfer insulators, such as WSe2/WS2 or TMD homobilayers under an applied electric field.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PHYSREVB.102.235423
