Thickness-dependent electronic structure in WTe2 thin films

Abstract

X. (2018). Thickness-dependent electronic structure in WTe2 thin films. Physical Review B: Covering condensed matter and materials physics, 98 (3), 035115-1-035115-10. Thickness-dependent electronic structure in WTe2 thin films AbstractWe study the electronic structure of WTe2 thin films with different thicknesses. High-quality thin-film samples are obtained with carrier mobility up to 5000 cm2 V−1 s−1, which enables us to resolve the four main Fermi pockets from Shubnikov-de Haas (SdH) oscillations. Angle-resolved SdH oscillations show that the WTe2 thin films cross from three-dimensional to two-dimensional electronic systems at a thickness of ∼ 20 nm. Using the field effect, the nature of the Fermi pockets in thin-film WTe2 is identified, and the evolution of SdH oscillation frequencies is traced over different sample thicknesses. It is found that the frequencies dramatically decrease at a thickness of approximately 12 nm, which indicates the onset of finite-size effects on the band structure. Our work pins down two critical length scales of the thickness-dependent electronic structure in WTe2 thin films. Disciplines Engineering | Physical Sciences and Mathematics Publication DetailsXiang, F., Srinivasan, A., Du, Z. Z., Klochan, O., Dou, S., Hamilton, A. We study the electronic structure of WTe 2 thin films with different thicknesses. High-quality thin-film samples are obtained with carrier mobility up to 5000 cm 2 V −1 s −1 , which enables us to resolve the four main Fermi pockets from Shubnikov-de Haas (SdH) oscillations. Angle-resolved SdH oscillations show that the WTe 2 thin films cross from three-dimensional to two-dimensional electronic systems at a thickness of ∼ 20 nm. Using the field effect, the nature of the Fermi pockets in thin-film WTe 2 is identified, and the evolution of SdH oscillation frequencies is traced over different sample thicknesses. It is found that the frequencies dramatically decrease at a thickness of approximately 12 nm, which indicates the onset of finite-size effects on the band structure. Our work pins down two critical length scales of the thickness-dependent electronic structure in WTe 2 thin films.

A room-temperature ferroelectric semimetal

“…1, D and E). These oscillations confirm the existence of four well-defined Fermi surfaces, consisting of two sets of electron and hole pockets ( 25 ). The presence of both free electrons and holes is believed to be the origin of the extremely large, nonsaturated magnetoresistance in WTe 2 ( 26 – 28 ).…”

“…In this configuration, the electrical current flow across the WTe 2 is strongly suppressed (fig. S3), although the WTe 2 flake is still metallic ( 25 ).…”

Quantum transport characteristics of heavily doped bismuth selenide nanoribbons

“…However, as the period of SdHOs depends inversely on the cross sectional area of the Fermi surface, it will be difficult to observe SdHOs from a relatively large Fermi surface. 23,27,28 Therefore, the result confirms that 2DEG has the dominant role in the collective SdHO signals, which may be because of the relatively small cross sectional area of its Fermi surface and the relatively high carrier density and mobility. The general expression for SdHOs can be described by 23 ΔRðBÞ…”

Van der Waals thin films of WTe2 for natural hyperbolic plasmonic surfaces

“…grapheme, MoS2), it can be treated as a real 2D plasmonic system since the plasmon wavelength is much larger than the film thickness. In fact, it is in principle possible to observe the same hyperbolic plasmons down to about 12 nm, above which the electronic structure is reported to remain the same as that of the thick film 43 . For few layer WTe2 films, the band structures are dramatically modified due to finite-size effects, and it becomes a 2D topological insulator in monolayer limit 44 .…”