Holstein polaron in a valley-degenerate two-dimensional semiconductor

Mingu Kang; Sung Won Jung; Woo Jong Shin; Yeongsup Sohn; Sae Hee Ryu; Timur K. Kim; Moritz Hoesch; Keun Su Kim

doi:10.1038/s41563-018-0092-7

Holstein polaron in a valley-degenerate two-dimensional semiconductor

Mingu Kang, Sung Won Jung, Woo Jong Shin, Yeongsup Sohn, Sae Hee Ryu, Timur K. Kim, Moritz Hoesch, Keun Su Kim

Department of Physics

Research output: Contribution to journal › Article › peer-review

64 Citations (Scopus)

Abstract

Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density¹. Carrier doping to 2D semiconductors can be used to modulate many-body interactions² and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)^3–5, which has been proposed to play a key role in high-temperature superconductivity⁶ and carrier mobility in devices⁷. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS₂, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently^8–11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons^12–18. The short-range nature of electron–phonon (e–ph) coupling in MoS₂ can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.

Original language	English
Pages (from-to)	676-680
Number of pages	5
Journal	Nature materials
Volume	17
Issue number	8
DOIs	https://doi.org/10.1038/s41563-018-0092-7
Publication status	Published - 2018 Aug 1

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (grants no. 2017R1A5A1014862 and no. 2017R1A2B3011368), Future-leading Research Initiative 2017-22-0059 of Yonsei University, and the POSCO Science Fellowship of POSCO TJ Park Foundation. This work was carried out with the support of the Diamond Light Source (beamline I05). The work at the Advanced Light Source was supported by the US Department of Energy, Office of Sciences under contract no. DE-AC02-05CH11231. M.K. acknowledges the Samsung Scholarship from Samsung Foundation of Culture. We thank A. Bostwick, C. Jozwiak and E. Rotenberg for help in the ARPES experiments, and R. Comin for helpful discussions.

Publisher Copyright:
© 2018, The Author(s).

All Science Journal Classification (ASJC) codes

Chemistry(all)
Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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10.1038/s41563-018-0092-7

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title = "Holstein polaron in a valley-degenerate two-dimensional semiconductor",

abstract = "Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density1. Carrier doping to 2D semiconductors can be used to modulate many-body interactions2 and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)3–5, which has been proposed to play a key role in high-temperature superconductivity6 and carrier mobility in devices7. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS2, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently8–11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons12–18. The short-range nature of electron–phonon (e–ph) coupling in MoS2 can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.",

author = "Mingu Kang and Jung, {Sung Won} and Shin, {Woo Jong} and Yeongsup Sohn and Ryu, {Sae Hee} and Kim, {Timur K.} and Moritz Hoesch and Kim, {Keun Su}",

note = "Funding Information: This work was supported by the National Research Foundation of Korea (grants no. 2017R1A5A1014862 and no. 2017R1A2B3011368), Future-leading Research Initiative 2017-22-0059 of Yonsei University, and the POSCO Science Fellowship of POSCO TJ Park Foundation. This work was carried out with the support of the Diamond Light Source (beamline I05). The work at the Advanced Light Source was supported by the US Department of Energy, Office of Sciences under contract no. DE-AC02-05CH11231. M.K. acknowledges the Samsung Scholarship from Samsung Foundation of Culture. We thank A. Bostwick, C. Jozwiak and E. Rotenberg for help in the ARPES experiments, and R. Comin for helpful discussions. Publisher Copyright: {\textcopyright} 2018, The Author(s).",

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AU - Hoesch, Moritz

AU - Kim, Keun Su

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N2 - Two-dimensional (2D) crystals have emerged as a class of materials with tunable carrier density1. Carrier doping to 2D semiconductors can be used to modulate many-body interactions2 and to explore novel composite particles. The Holstein polaron is a small composite particle of an electron that carries a cloud of self-induced lattice deformation (or phonons)3–5, which has been proposed to play a key role in high-temperature superconductivity6 and carrier mobility in devices7. Here we report the discovery of Holstein polarons in a surface-doped layered semiconductor, MoS2, in which a puzzling 2D superconducting dome with the critical temperature of 12 K was found recently8–11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons12–18. The short-range nature of electron–phonon (e–ph) coupling in MoS2 can be explained by its valley degeneracy, which enables strong intervalley coupling mediated by acoustic phonons. The coupling strength is found to increase gradually along the superconducting dome up to the intermediate regime, which suggests a bipolaronic pairing in the 2D superconductivity.

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Holstein polaron in a valley-degenerate two-dimensional semiconductor

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