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Abstract Excitons are spin integer particles that are predicted to condense into a coherent quantum state at sufficiently low temperature. Here by using photocurrent imaging we report experimental evidence of formation and efficient transport of non-equilibrium excitons in Bi2-xSbxSe3nanoribbons. The photocurrent distributions are independent of electric field, indicating that photoexcited electrons and holes form excitons. Remarkably, these excitons can transport over hundreds of micrometers along the topological insulator (TI) nanoribbons before recombination at up to 40 K. The macroscopic transport distance, combined with short carrier lifetime obtained from transient photocurrent measurements, indicates an exciton diffusion coefficient at least 36 m2 s−1, which corresponds to a mobility of 6 × 104 m2 V−1 s−1at 7 K and is four order of magnitude higher than the value reported for free carriers in TIs. The observation of highly dissipationless exciton transport implies the formation of superfluid-like exciton condensate at the surface of TIs.
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Mott‐Limited Thermopower of Pascal Electron Liquid Phases at the LaAlO3/SrTiO3 Interface
The thermoelectric properties of quasi‐1D electron waveguides at the LaAlO3/SrTiO3interface at millikelvin temperatures are investigated. A highly enhanced and oscillating thermopower is found for these electron waveguides, with values exceeding 100 μV K−1at 0.1 K in the electron‐depletion regime. The Mott relation, which governs the band‐term thermopower of noninteracting electrons, agrees well with the experimental findings in and around regimes where strongly attractive electron–electron interactions lead to a previously reported Pascal series of conductance explained by bound states of electrons. These results pave the way for quantized thermal transport studies of emergent electron liquid phases in which transport is governed by quasiparticles with charges that are integer multiples or fractions of an electron.
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- Award ID(s):
- 2225888
- PAR ID:
- 10477124
- Publisher / Repository:
- Physica Status Solidi b
- Date Published:
- Journal Name:
- physica status solidi (b)
- Volume:
- 260
- Issue:
- 6
- ISSN:
- 0370-1972
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/pssb.202200612
