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Title: Giant spin-splitting and gap renormalization driven by trions in single-layer WS 2/h-BN heterostructures

Abstract

In two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), new electronic phenomena such as tunable bandgaps and strongly bound excitons and trions emerge from strong many-body effects, beyond the spin and valley degrees of freedom induced by spin-orbit coupling and by lattice symmetry. Combining single-layer TMDs with other 2D materials in van der Waals heterostructures offers an intriguing means of controlling the electronic properties through these many-body effects, by means of engineered interlayer interactions. Here, we use micro-focused angle-resolved photoemission spectroscopy (microARPES) and in situ surface doping to manipulate the electronic structure of single-layer WS 2 on hexagonal boron nitride (WS 2/h-BN). Upon electron doping, we observe an unexpected giant renormalization of the spin-orbit splitting of the single-layer WS 2 valence band, from 430 meV to 660 meV, together with a bandgap reduction of at least 325 meV, attributed to the formation of trionic quasiparticles. Furthermore, these findings suggest that the electronic, spintronic and excitonic properties are widely tunable in 2D TMD/h-BN heterostructures, as these are intimately linked to the quasiparticle dynamics of the materials.

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [3]; ORCiD logo [4];  [1];  [1]; ORCiD logo [4]; ORCiD logo [1];  [3]; ORCiD logo [3]; ORCiD logo [3]
  1. The Ohio State Univ., Columbus, OH (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Aarhus Univ., Aarhus C (Denmark)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. Naval Research Lab., Washington, D.C. (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1462967
Grant/Contract Number:  
AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Nature Physics
Additional Journal Information:
Journal Volume: 14; Journal Issue: 4; Related Information: © 2017 The Author(s).; Journal ID: ISSN 1745-2473
Publisher:
Nature Publishing Group (NPG)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Katoch, Jyoti, Ulstrup, Soren, Koch, Roland J., Moser, Simon, McCreary, Kathleen M., Singh, Simranjeet, Xu, Jinsong, Jonker, Berend T., Kawakami, Roland K., Bostwick, Aaron, Rotenberg, Eli, and Jozwiak, Chris. Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures. United States: N. p., 2018. Web. doi:10.1038/s41567-017-0033-4.
Katoch, Jyoti, Ulstrup, Soren, Koch, Roland J., Moser, Simon, McCreary, Kathleen M., Singh, Simranjeet, Xu, Jinsong, Jonker, Berend T., Kawakami, Roland K., Bostwick, Aaron, Rotenberg, Eli, & Jozwiak, Chris. Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures. United States. doi:10.1038/s41567-017-0033-4.
Katoch, Jyoti, Ulstrup, Soren, Koch, Roland J., Moser, Simon, McCreary, Kathleen M., Singh, Simranjeet, Xu, Jinsong, Jonker, Berend T., Kawakami, Roland K., Bostwick, Aaron, Rotenberg, Eli, and Jozwiak, Chris. Mon . "Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures". United States. doi:10.1038/s41567-017-0033-4. https://www.osti.gov/servlets/purl/1462967.
@article{osti_1462967,
title = {Giant spin-splitting and gap renormalization driven by trions in single-layer WS2/h-BN heterostructures},
author = {Katoch, Jyoti and Ulstrup, Soren and Koch, Roland J. and Moser, Simon and McCreary, Kathleen M. and Singh, Simranjeet and Xu, Jinsong and Jonker, Berend T. and Kawakami, Roland K. and Bostwick, Aaron and Rotenberg, Eli and Jozwiak, Chris},
abstractNote = {In two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs), new electronic phenomena such as tunable bandgaps and strongly bound excitons and trions emerge from strong many-body effects, beyond the spin and valley degrees of freedom induced by spin-orbit coupling and by lattice symmetry. Combining single-layer TMDs with other 2D materials in van der Waals heterostructures offers an intriguing means of controlling the electronic properties through these many-body effects, by means of engineered interlayer interactions. Here, we use micro-focused angle-resolved photoemission spectroscopy (microARPES) and in situ surface doping to manipulate the electronic structure of single-layer WS2 on hexagonal boron nitride (WS2/h-BN). Upon electron doping, we observe an unexpected giant renormalization of the spin-orbit splitting of the single-layer WS2 valence band, from 430 meV to 660 meV, together with a bandgap reduction of at least 325 meV, attributed to the formation of trionic quasiparticles. Furthermore, these findings suggest that the electronic, spintronic and excitonic properties are widely tunable in 2D TMD/h-BN heterostructures, as these are intimately linked to the quasiparticle dynamics of the materials.},
doi = {10.1038/s41567-017-0033-4},
journal = {Nature Physics},
issn = {1745-2473},
number = 4,
volume = 14,
place = {United States},
year = {2018},
month = {1}
}

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Cited by: 15 works
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Figures / Tables:

Fig. 1 Fig. 1: Spatially-resolved electronic structure mapping of a WS2/h-BN heterostructure supported on TiO2. a, Side-view sketch of WS2/h-BN on TiO2, illustrating SL WS2 regions contacted directly to h-BN and to TiO2. b, Optical microscope image of the sample. The contrast has been strongly enhanced to better visualize the SL WS2.more » Brown patches correspond to bare TiO2, light purple to WS2/TiO2 and the darker green/red structure is the h-BN flake. c, Spatial map of photoemission intensity (integrated over the red box in (d)) for the same region seen in b. See Supplementary Section 1 for details on the spatial intensity variations. d, Measured dispersion along the $ \overline{K}\ \overline{Γ}\ \overline{K'}\ $ direction of the SL WS2 BZ (see green BZ and dashed red line in the insert) collected at the spatial coordinates marked by a white arrow in c. The rectangular red box marks a region with crossing WS2 and h-BN bands where the photoemission intensity is integrated to produce the spatial map in c. e, ARPES dispersion in the high symmetry direction of h-BN (see purple BZ and dashed black line in the insert). f-h, Constant energy cuts obtained at the given binding energies (see also ticks on the right of panels d-e). Arrows mark distinct energy contours relating to SL WS2 and to h-BN. The red and black dashed lines (insert in d-e) indicate a twist angle of (23 ± 1)° in between the SL WS2 and h-BN. i-j, EDCs obtained along the dotted lines in d-e around the h-BN VBM (i) and SL WS2 VBM (j). The positions of the band edges are given in units of eV and the error bar is 30 meV.« less

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Works referenced in this record:

Van der Waals heterostructures
journal, July 2013

  • Geim, A. K.; Grigorieva, I. V.
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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.