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Temperature-independent band structure of WTe2 as observed from angle-resolved photoemission spectroscopy

S. Thirupathaiah, Rajveer Jha, Banabir Pal, J. S. Matias, P. Kumar Das, I. Vobornik, R. A. Ribeiro, and D. D. Sarma
Phys. Rev. B 96, 165149 – Published 27 October 2017
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  • INTRODUCTION
  • EXPERIMENTAL AND BAND STRUCTURE…
  • RESULTS AND DISCUSSION
  • CONCLUSIONS
  • ACKNOWLEDGMENTS
    • References

    Abstract

    Extremely large magnetoresistance (XMR), observed in transition-metal dichalcogenides, WTe2, has attracted recently a great deal of research interest as it shows no sign of saturation up to a magnetic field as high as 60 T, in addition to the presence of type-II Weyl fermions. Currently, there is a great deal of discussion on the role of band structure changes in the temperature-dependent XMR in this compound. In this contribution, we study the band structure of WTe2 using angle-resolved photoemission spectroscopy and first-principles calculations to demonstrate that the temperature-dependent band structure has no substantial effect on the temperature-dependent XMR, as our measurements do not show band structure changes upon increasing the sample temperature between 20 and 130 K. We further observe an electronlike surface state, dispersing in such a way that it connects the top of bulk holelike band to the bottom of bulk electronlike band. Interestingly, similarly to bulk states, the surface state is also mostly intact with the sample temperature. Our results provide valuable information in shaping the mechanism of temperature-dependent XMR in WTe2.

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    • Received 23 May 2017
    • Revised 12 September 2017

    DOI:https://doi.org/10.1103/PhysRevB.96.165149

    ©2017 American Physical Society

    Physics Subject Headings (PhySH)

    1. Research Areas
    Electronic structureFermi surfaceMagnetoresistanceSpin-orbit couplingWeyl fermions
    1. Physical Systems
    Weyl semimetal
    1. Techniques
    Angle-resolved photoemission spectroscopy
    Condensed Matter, Materials & Applied Physics

    Authors & Affiliations

    S. Thirupathaiah1,*, Rajveer Jha2, Banabir Pal1, J. S. Matias2, P. Kumar Das3,4, I. Vobornik3, R. A. Ribeiro2, and D. D. Sarma1

    • 1Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore, Karnataka 560012, India
    • 2CCNH, Universidade Federal do ABC (UFABC), Santo Andre, SP, 09210-580, Brazil
    • 3CNR-IOM, TASC Laboratory AREA Science Park-Basovizza, 34149 Trieste, Italy
    • 4International Centre for Theoretical Physics, Strada Costiera 11, 34100 Trieste, Italy

    • *t.setti@iisc.ac.in

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    Issue

    Vol. 96, Iss. 16 — 15 October 2017

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    Images

    • Figure 1
      Figure 1

      (a) Orthorhombic crystal structure of WTe2. (b) 3D view of the bulk Brillouin zone on which the high symmetry points are located. (c) Band structure of WTe2 from the DFT calculations performed without and with spin-orbit coupling (SOC). (d) 3D view of the Fermi surface map derived without SOC. (e) Angle-integrated photoemission spectra with the core-level energy positions labeled; the zoomed-in valence spectra are shown in the inset. (f) Schematic of a typical measuring geometry in which the s- and p-plane polarized lights are denoted with respect to the analyzer entrance slit (ES) and the scattering plane (SP).

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    • Figure 2
      Figure 2

      ARPES data of WTe2. The data are measured using p-polarized light with a photon energy of hν=20 eV. The data shown in (a)–(c) are measured at a sample temperature of 20 K. Panel (a) depicts the Fermi surface (FS) map. Hole and electron pockets are schematically shown by blue and red color solid contours (contribution from bulk), and the green color contour is the Fermi arc from the surface. Panel (b) shows the energy distribution map (EDM) taken along cut 1 as shown on the FS map. Top panels in (c) show EDMs taken along cuts 2–6 from left to right, respectively. Bottom panels in (c) are the respective second derivatives of the EDMs shown in the top panels. On the EDMs in (b) and (c) the band dispersions are schematically shown. Panels (d)–(f) depict similar data of (a)–(c) except that these are measured at 130 K. Panels (g) and (h) depict the orbital-resolved band structure from the calculations plotted for W 5d and Te 5p orbital characters, respectively.

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    • Figure 3
      Figure 3

      (a) Top panels show temperature-dependent EDMs along cut 1 and the bottom ones show temperature-dependent EDMs along cut 3. (b) Momentum-dispersive curves (MDCs) from the EDMs of cut 1, extracted by integrating over an energy window of 10 meV centered at the Fermi level. Overlapped intensity plot of MDCs measured at 20 and 130 K is shown in the inset of (b). (c) Energy-dispersive curves (EDCs) taken at k||=0 from the EDMs of cut 1. Overlapped intensity plot of EDCs measured at 20 and 130 K is shown in the inset. (d) Similar data to (c), but taken from the EDMs of cut 3. (e) Shows EDCs taken from the EDMs (see inset) of cut 2 measured at two temperatures, 20 and 130 K.

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