Symmetry induced pairing in dark excitonic condensate at finite temperature

Abstract

Bose Einstein condensate of dark intervalley excitons must be inherently multi-component because of crystalline symmetries. Since valleys hosting such excitons are separated by large quasi-momenta, a minimal inter-component Josephson-type coupling can only be established between pairs of excitons from the time-reversed valleys. As a result, a paired condensate can emerge at finite temperature, that is, the off-diagonal order exists for the pairs from the time-reversed valleys, while the individual valleys are disordered. This prediction follows from the elementary mean field analysis regardless of the dimensionality. However, as Monte Carlo simulations show, no such a phase exists in 3D crystals. Instead, the multi-component condensation proceeds as the Ist order transition from the normal state. The paired phase does exist in 2D for the number of the components $N_v\ge 6$. It forms by Berezinskii-Kosterlitz-Thouless transition from the high temperature (normal) phase. The multi-component condensate appears upon further lowering of temperature.

Adham passed away before this project was completed. In this new version, typos are fixed and more explanations are added

References in corpus (8)

• A superconductor to superfluid phase transition in liquid metallic hydrogen
• Dark excitons in transition metal dichalcogenides
• Correlated insulator of excitons in WSe2/WS2 moiré superlattices
• Composite fermion state of spin-orbit coupled bosons
• Spontaneous formation of a non-uniform chiral spin liquid in moat-band lattices
• Excitonic topological order in imbalanced electron-hole bilayers
• Phonon-induced modification of polaritonic Rabi oscillations in the presence of the dark excitonic condensate
• Borromean supercounterfluids at finite temperatures

Cited by in corpus (1)

• Vestigial $d$-wave charge-$4e$ Superconductivity from Bidirectional Pair Density Waves