Evidence for a topological excitonic insulator in InAs/GaSb bilayers

Du, Lingjie; Li, Xinwei; Lou, Wenkai; Sullivan, Gerard; Chang, Kai; Kono, Junichiro; Du, Rui-Rui

doi:10.1038/s41467-017-01988-1

Evidence for a topological excitonic insulator in InAs/GaSb bilayers

Journal Article · Thu Dec 07 00:00:00 EST 2017 · Nature Communications

DOI:https://doi.org/10.1038/s41467-017-01988-1· OSTI ID:1499925

Du, Lingjie ^[1]; Li, Xinwei ^[2]; ^[3]; Sullivan, Gerard ^[4]; Chang, Kai ^[3]; Kono, Junichiro ^[2]; Du, Rui-Rui ^[5]

Rice Univ., Houston, TX (United States); Rice University
Rice Univ., Houston, TX (United States)
Chinese Academy of Sciences (CAS), Beijing (China)
Teledyne Scientific and Imaging, Thousand Oaks, CA (United States)
Rice Univ., Houston, TX (United States); Peking Univ., Beijing (China)

Electron–hole pairing can occur in a dilute semimetal, transforming the system into an excitonic insulator state in which a gap spontaneously appears at the Fermi surface, analogous to a Bardeen–Cooper–Schrieffer (BCS) superconductor. Here, we report optical spectroscopic and electronic transport evidence for the formation of an excitonic insulator gap in an inverted InAs/GaSb quantum-well system at low temperatures and low electron–hole densities. Terahertz transmission spectra exhibit two absorption lines that are quantitatively consistent with predictions from the pair-breaking excitation dispersion calculated based on the BCS gap equation. Low-temperature electronic transport measurements reveal a gap of ~2 meV (or ~25 K) with a critical temperature of ~10 K in the bulk, together with quantized edge conductance, suggesting the occurrence of a topological excitonic insulator phase.

View Accepted Manuscript (DOE)

Research Organization:: Rice Univ., Houston, TX (United States)

Sponsoring Organization:: USDOE

Grant/Contract Number:: FG02-06ER46274

OSTI ID:: 1499925

Journal Information:: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 8; ISSN 2041-1723

Publisher:: Nature Publishing GroupCopyright Statement

Country of Publication:: United States

Language:: English

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