Small exciton effective mass in QL Bi2Se2Te: A material platform towards high-temperature excitonic condensate

TL;DR

This study predicts that monolayer Bi2Se2Te can host high-temperature excitonic Bose-Einstein condensation and superfluidity due to its unique electronic properties, making it a promising platform for excitonic physics research.

Contribution

First-principles and many-body calculations reveal that Bi2Se2Te monolayer can achieve high-temperature excitonic condensation with large exciton radius and small effective mass.

Findings

Predicted phase transition temperatures of ~257 K for BEC and ~64.25 K for superfluidity.

Identified the role of spin-orbit coupling and selection rules in excitonic properties.

Suggested potential for experimental realization of high-temperature excitonic phenomena.

Abstract

Using first-principles simulations combined with many-body calculations, we show that two-dimensional free-standing quintuple-layer Bi2Se2Te is an inversion symmetric monolayer expected to achieve spatially indirect exciton with large exciton radius, small exciton effective mass and long exciton lifetime. Such system is theoretically predicted to be a promising platform for realizing excitonic Bose-Einstein condensation and superfluid due to its high phase transition temperatures of ~257 K and ~64.25 K for the BEC and excitonic superfluid, respectively. The importance of spin-orbit coupling is revealed, and the angular momentum selection rules for photon absorption are discussed. This finding suggests the potential of QL Bi2Se2Te monolayer with exotic bosonic bound states provides as a tantalizing high-temperature platform to probe excitonic physics.