Anisotropic Shubnikov-de Haas effect in topological Weyl semimetal MoTe2

Abstract

Newly emergent type-II Weyl semimetals with topological surface states so-called Fermi arcs have attracted much attention for their novel physical properties and potential application in quantum devices. Here, we investigate the in-plane anisotropic structure and inversion symmetry breaking by angle-resolved polarized Raman and second harmonic generation and observe the anisotropic Shubnikov-de Haas effect in Weyl Semimetal MoTe2, which is only present in the b-axis (armchair chain) direction. First-principles calculation depicts the type-II Weyl points and clear topological Fermi arcs. A nontrivial π Berry's phase from Landau quantization and an extra-quantum oscillation frequency arising by Weyl orbit are obtained, which provide evidence for the existence of an anisotropic type-II Weyl state in MoTe2. This work reveals the nontrivial topological surface state of Weyl semimetal MoTe2 in both theory and experiment, providing a promising platform for unique physical properties and applications in quantum information processing.

Two‐Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications

“…Reproduced with permission. [ 83 ] Copyright 2021, AIP Publishing. f) Hall resistance ( R Hall ) curves of the 2D Bi 2 Se 3 thin film at different temperatures.…”

“…doping, [65,[198][199][200] and field-effect gating. [4,55,80,167] In particular, 2D vdW TMs often exhibit exotic transport properties such as giant magnetoresistances, [45,80,81,109,224] quantum oscillation, [46,72,82,83,199] QHE, [47,57] superconductivity, [110,193,225] weak localization (WL) and weak antilocalization (WAL). [6,55,58,226,227] These transport phenomena are of great significance to understand the nature of 2D vdW TMs.…”

“…Up to now, quantum oscillation phenomena has been observed in various 2D vdW TMs, such as Sb 2 Te 3 , [46] Sb 2-x V x Te 3 , [199] T d -WTe 2 , [72,82] and T d -MoTe 2 . [83] The magnetotransport in the surface and bulk of 2D vdW TMs bring very different quantum phenomena, and quantum oscillation is an effective way to determine the transport channel of 2D vdW TMs, especially for 2D vdW TIs with gapless Dirac-like surface states with linear dispersions. [46] In general, quantum oscillations are mainly concerned with longitudinal resistance of 2D vdW TMs, while Felser et al [199] reported the oscillation in both longitudinal resistance and Hall resistance in 2D Sb 2-x V x Te 3 thin film, a vdW ferromagnetic TIs (Figure 10a).…”

“…[262] Especially, due to the typical anisotropic Fermi surface in some WSMs such as T d -MoTe 2 and WTe 2 , the anisotropic quantum oscillations along the b-axis (armchair chains) of 2D T d -MoTe 2 nanosheet were observed (Figure 10d). [72,83] Further, owing to the strongly different band dispersion along the different 2D WSM crystal axis, the different Fermi velocity leads to the absent quantum oscillations in 2D T d -MoTe 2 nanosheet when electrical transport measurement is along the a-axis (zigzag chains) (Figure 10e).…”

“…[74,75] All of them are classified as type-II WSM, which is realized by broken the Lorentz invariance of type-I WSM. [76] 2D vdW WSMs T d -WTe 2 and T d -MoTe 2 exhibit rich, tunable physical properties (e.g., gate/magnetic field tuned superconductivity, [77,78] anisotropic photoresponse, [79] giant MR, [80,81] quantum oscillation, [72,82,83] robust room-temperature ferroelectric switching, [10,84] robust spin polarization and ultrafast spin relaxation [85,86] ) and great application potential in memories, [87,88] spintronic devices [89][90][91] and photodetectors. [92,93] Besides, ternary telluride TaIrTe 4 , [94] NbIrTe 4 , [95] and TaFeTe 4 [96] are also experimentally demonstrated to the vdW type-II WSM with broadband anisotropic photoresponse [11] and strong in-plane electrical anisotropy.…”