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SUMMARY:Field control of many-body phases in frustrated moiré bilayers -
  Laura Classen\, MPI Stuttgart
DTSTART:20240208T140000Z
DTEND:20240208T150000Z
UID:TALK209764@talks.cam.ac.uk
CONTACT:Gaurav
DESCRIPTION:We determine the ground states and excitation spectra of the p
 aradigmatic four-flavour Heisenberg model with nearest- and next-nearest-n
 eighbor exchange couplings on the triangular lattice in a field controllin
 g the population imbalance of flavor pairs. Such a system arises in the st
 rongly correlated limit of moiré bilayers of transition metal dichalcoge
 nides in an electric displacement field or in-plane magnetic field\, and c
 an be simulated via ultracold alkaline-earth atoms. We argue that the fiel
 d tunes between effective SU(4) and SU(2) symmetries in the balanced and f
 ully polarised limits and employ a combination of mean-field calculations\
 , flavour-wave theory\, and exact diagonalisation to analyse the intermedi
 ate\, imbalanced regime. We find different symmetry-broken phases with sim
 ultaneous spin and excitonic order depending on the field and next-nearest
 -neighbor coupling. Furthermore\, we demonstrate that there is a strongly 
 fluctuating regime without long-range order that connects candidate spin l
 iquids of the SU(2) and SU(4) limit. The strong fluctuations are facilitat
 ed by an extensive classical degeneracy of the model\, and we argue that t
 hey are also responsible for a strong polarisability at 1/3 polarisation t
 hat survives from the mean-field level to the exact spectrum.
LOCATION:TCM Seminar Room
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