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Holstein polaron in a valley-degenerate two-dimensional semiconductor

DOI: 10.1038/s41563-018-0092-7 DOI Help

Authors: Mingu Kang (Yonsei University; Massachusetts Institute of Technology) , Sung Won Jung (Yonsei University; Pohang University of Science and Technology) , Woo Jong Shin (Yonsei University; Pohang University of Science and Technology) , Yeongsup Sohn (Yonsei University; Pohang University of Science and Technology) , Sae Hee Ryu (Yonsei University; Pohang University of Science and Technology) , Timur K. Kim (Diamond Light Source) , Moritz Hoesch (Diamond Light Source) , Keun Su Kim (Yonsei University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Materials , VOL 306

State: Published (Approved)
Published: May 2018

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)3,4,5, 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 recently8,9,10,11. Using a high-resolution band mapping of charge carriers, we found strong band renormalizations collectively identified as a hitherto unobserved spectral function of Holstein polarons12,13,14,15,16,17,18. 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.

Journal Keywords: Superconducting properties and materials; Two-dimensional materials

Subject Areas: Materials, Physics

Instruments: I05-ARPES

Other Facilities: Advanced Light Source

Added On: 31/05/2018 15:33

Discipline Tags:

Materials Science Quantum Materials Superconductors Physics

Technical Tags:

Spectroscopy Angle Resolved Photoemission Spectroscopy (ARPES)