Metal-Insulator Transition and Emergent Gapped Phase in the Surface-Doped 2D Semiconductor 2H-MoTe${}_2$

Abstract

Artificially created two-dimensional (2D) interfaces or structures are ideal for seeking exotic phase transitions due to their highly tunable carrier density and interfacially enhanced many-body interactions. Here, we report the discovery of a metal-insulator transition (MIT) and an emergent gapped phase in the metal-semiconductor interface that is created in 2H-MoTe${}_2$ via alkali-metal deposition. Using angle-resolved photoemission spectroscopy, we found that the electron-phonon coupling is strong at the interface as characterized by a clear observation of replica shake-off bands. Such strong electron-phonon coupling interplays with disorder scattering, leading to an Anderson localization of polarons which could explain the MIT. The domelike emergent gapped phase could then be attributed to a polaron extended state or phonon-mediated superconductivity. Our results demonstrate the capability of alkali-metal deposition as an effective method to enhance the many-body interactions in 2D semiconductors. The surface-doped 2H-MoTe${}_2$ is a promising candidate for realizing polaronic insulator and high-$T_c$ superconductivity.

11 pages, 4 figures, See Supplemental Material at http://link.aps.org/ supplemental/10.1103/PhysRevLett.126.106602

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• Anderson Transitions
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Universal Mechanism of Band-Gap Engineering in Transition-Metal Dichalcogenides
• Double resonance Raman modes in mono- and few-layer MoTe${}_2$
• Phase Diagram of Electron Doped Dichalcogenides

Cited by in corpus (1)

• Evolution of the electronic structure of ultrathin MnBi2Te4 Films