Perfect charge compensation in WTe<sub>2</sub>for the extraordinary magnetoresistance: From bulk to monolayer

Lv, Huiying; Lu, W. J.; Shao, Ding-Fu; Liu, Yu; Tan, S. G.; Sun, Yi‐Yang

doi:10.1209/0295-5075/110/37004

Cited by 103 publications

(84 citation statements)

References 28 publications

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“…Bulk WTe 2 exhibits a nonsaturated and extremely large magnetoresistance (MR) which could be used to design devices such as magnetic sensors [1]. It is believed that the peculiar magnetoresistance occurs due to the nearly equal electron and hole concentrations with high carrier mobility [1][2][3][4][5][6][7][8], and forbidden backscattering due to strong spin-orbit coupling also plays an important role [9]. Surprisingly, although WTe 2 is a layered material, the anisotropy of the effective mass is small [10], and quantum oscillations can be observed along three different crystal axes [3,11], which makes it essentially a three-dimensional (3D) instead of two-dimensional (2D) electronic system [12].…”

Section: Introductionmentioning

confidence: 99%

Thickness-dependent electronic structure in WTe2 thin films

Xiang

Srinivasan

et al. 2018

Phys. Rev. B

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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.

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Section: Introductionmentioning

confidence: 99%

Thickness-dependent electronic structure in WTe2 thin films

Xiang

Srinivasan

et al. 2018

Phys. Rev. B

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“…Tungsten telluride (WTe 2 ), as a typical transition-metal dichalcogenide (TMD), has attracted great attention recently owing to the interesting physical properties [1][2][3][4][5][6][7][8][9][10][11][12], such as non-saturating giant positive magnetoresistance [1,3], superconductivity [8,9] and high carrier mobilities [5]. Unfortunately, the extremely large positive magnetoresistance can only be observed at low temperature which limits the applications of WTe 2 magnetorestance devices.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of lattice thermal conductivity of Td–WTe₂

et al. 2016

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The structural and thermal properties of bulk Td-WTe 2 have been studied by using first-principles calculations based on the simple Klemens model and an iterative self-consistent method. Both methods show that lattice thermal conductivity is anisotropic, with the highest value in the (001) plane, and lowest one along the c-axis at 300 K. The calculated average thermal conductivity of WTe 2 is in agreement with the experimental measurement. The size dependent thermal conductivity shows that nanostructuring of WTe 2 can possibly further decrease the lattice thermal conductivity, which can improve the thermoelectric efficiency. Such extremely low thermal conductivity, even much lower than WSe 2 , makes WTe 2 having many potential applications in thermal insulation and thermoelectric materials.

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“…To understand the phase transition, the proper treatment of long and short range interlayer interaction in TMDs is essential. Most of the theoretical studies, however, fail to reproduce the experimental crystal structures of the two phases of MoTe 2 and WTe 2 so do their topological electronic structures using crystal structures obtained from ab initio calculations [24][25][26][27][28][29][30] . Instead, the atomic structures from experiment data are routinely used to understand and predict the low energy electronic properties 4,18,[31][32][33][34][35] .…”

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Origins of the structural phase transitions in MoTe2 and WTe2

et al. 2017

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Layered transition metal dichalcogenides MoTe2 and WTe2 share almost similar lattice constants as well as topological electronic properties except their structural phase transitions. While the former shows a first-order phase transition between monoclinic and orthorhombic structures, the latter does not. Using a recently proposed van der Waals density functional method, we investigate structural stability of the two materials and uncover that the disparate phase transitions originate from delicate differences between their interlayer bonding states near the Fermi energy. By exploiting the relation between the structural phase transitions and the low energy electronic properties, we show that a charge doping can control the transition substantially, thereby suggesting a way to stabilize or to eliminate their topological electronic energy bands. Because of the layered structures of TMDs, several polymorphs can exist and show characteristic physical properties depending on their structures 8 . A typical TMD shows the trigonal prismatic (2H) or the octahedral (1T ) structures 9-12 . For MoTe 2 and WTe 2 , the 2H structure (α-phase, P 6 3 /mmc) is a stable semiconductor while the 1T form is unstable 7,13 . The unstable 1T structure turns into the distorted octahedral one (1T ′ ) 7,14 . The stacked 1T ′ single layer forms a threedimensional bulk with the monoclinic structure (β-phase, P 2 1 /m) or the orthorhombic one (γ-phase, P mn2 1 ) (see Fig. 1) [15][16][17] . Interestingly, the β phase with a few layers is a potential candidate of QSH insulator 7 and the bulk γ phase shows type-II Weyl semimetalic energy bands 4,18,19 , respectively. Since the structural differences between β and γ phases are minute (∼4• tilting of axis along out-of-plane direction in β phase with respect to one in γ phase), the sensitive change in their topological low energy electronic properties is remarkable and the transition between different structures can lead to alternation of topological properties of the system.A phase transition between the β-and γ-phase in the layered TMDs has been known for a long time 16,20 . MoTe 2 shows a first-order transition from the β-to γ-structure at around 250 K 20 when temperature decreases. WTe 2 , however, does not show any transition and stays at the γ-phase 21,22 . Since the structural parameters of a single layer of 1T ′ -MoTe 2 and 1T ′ -WTe 2 are almost the same 15,17,23 and Mo and W belong to the same group in the periodic table, the different phase transition behaviors are intriguing and origins of the contrasting features are yet to be clarified. To understand the phase transition, the proper treatment of long and short range interlayer interaction in TMDs is essential. Most of the theoretical studies, however, fail to reproduce the experimental crystal structures of the two phases of MoTe 2 and WTe 2 so do their topological electronic structures using crystal structures obtained from ab initio calculations [24][25][26][27][28][29][30] . Instead, the atomic structures from experiment data are r...

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Perfect charge compensation in WTe₂for the extraordinary magnetoresistance: From bulk to monolayer

Cited by 103 publications

References 28 publications

Thickness-dependent electronic structure in WTe2 thin films

Thickness-dependent electronic structure in WTe2 thin films

First-principles study of lattice thermal conductivity of Td–WTe₂

Origins of the structural phase transitions in MoTe2 and WTe2

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Perfect charge compensation in WTe2for the extraordinary magnetoresistance: From bulk to monolayer

Cited by 103 publications

References 28 publications

Thickness-dependent electronic structure in WTe2 thin films

Thickness-dependent electronic structure in WTe2 thin films

First-principles study of lattice thermal conductivity of Td–WTe2

Origins of the structural phase transitions in MoTe2 and WTe2

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Perfect charge compensation in WTe₂for the extraordinary magnetoresistance: From bulk to monolayer

First-principles study of lattice thermal conductivity of Td–WTe₂