2022/07/22 by Huang, Yi, Shklovskii, B. I.
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.2207.11319
This paper is written for the Special Issue in Honor of Emmanuel Rashba. We study the gas of indirect dipolar excitons created by an interband illumination of a pentalayer WSe2/MoSe2/WSe2/MoSe2/WSe2. We show that two colinear indirect excitons bind into a linear biexciton with twice larger dipole moment. Two biexcitons with opposite dipole directions attract each other at large distances and repel each other at short distances. Therefore, biexcitons form a staggered crystal with anti-ferroelectric square lattice. The electrostatic energy of this crystal per biexciton has a minimum at the biexciton concentration n =nc=0.14d-2, where d ∼ 0.7 nm is a single layer thickness. At small illumination intensity, biexcitons condense into sparse crystallites with n = nc, where photoluminescence frequency is red shifted and independent on the light intensity. We also study a capacitor made of five identical semiconductor monolayers separated by hBN spacers where a critical voltage applied between layers 1, 3, 5, and 2, 4 abruptly creates a similar biexciton crystal. At this voltage, the differential capacitance diverges.