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Title: Electronic band tuning under pressure in MoTe 2 topological semimetal

Abstract

Topological superconductors (TSC) can host exotic quasiparticles such as Majorana fermions, poised as the fundamental qubits for quantum computers. TSC’s are predicted to form a superconducting gap in the bulk, and gapless surface/edges states which can lead to the emergence of Majorana zero energy modes. A candidate TSC is the layered dichalcogenide MoTe 2, a type-II Weyl (semi)metal in the non-centrosymmetric orthorhombic (Td) phase. It becomes superconducting upon cooling below 0.25 K, while under pressure, superconductivity extends well beyond the structural boundary between the orthorhombic and monoclinic (1T') phases. Here, we show that under pressure, coupled with the electronic band transition across the T d to 1T' phase boundary, evidence for a new phase, we call T d* is observed and appears as the volume fraction of the T d phase decreases in the coexistence region. T d* is most likely centrosymmetric. In the region of space where T d* appears, Weyl nodes are destroyed. T d* disappears upon entering the monoclinic phase as a function of temperature or on approaching the suppression of the orthorhombic phase under pressure above 1 GPa. Our calculations in the orthorhombic phase under pressure show significant band tilting around the Weyl nodes that mostmore » likely changes the spin-orbital texture of the electron and hole pockets near the Fermi surface under pressure that may be linked to the observed suppression of magnetoresistance with pressure.« less

Authors:
 [1];  [2];  [3];  [4]; ORCiD logo [5];  [6];  [2];  [2];  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duke Univ., Durham, NC (United States)
  2. Univ. of Virginia, Charlottesville, VA (United States)
  3. Central Michigan Univ., Mount Pleasant, MI (United States)
  4. Ames Lab., Ames, IA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  6. Chinese Academy of Sciences (CAS), Beijing (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1561665
Grant/Contract Number:  
AC05-00OR22725; FG02-01ER45927
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
npj Quantum Materials
Additional Journal Information:
Journal Volume: 4; Journal Issue: 1; Journal ID: ISSN 2397-4648
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY

Citation Formats

Dissanayake, Sachith, Duan, Chunruo, Yang, Junjie, Liu, Jun, Matsuda, Masaaki, Yue, Changming, Schneeloch, John A., Teo, Jeffrey C. Y., and Louca, Despina. Electronic band tuning under pressure in MoTe2 topological semimetal. United States: N. p., 2019. Web. doi:10.1038/s41535-019-0187-7.
Dissanayake, Sachith, Duan, Chunruo, Yang, Junjie, Liu, Jun, Matsuda, Masaaki, Yue, Changming, Schneeloch, John A., Teo, Jeffrey C. Y., & Louca, Despina. Electronic band tuning under pressure in MoTe2 topological semimetal. United States. doi:10.1038/s41535-019-0187-7.
Dissanayake, Sachith, Duan, Chunruo, Yang, Junjie, Liu, Jun, Matsuda, Masaaki, Yue, Changming, Schneeloch, John A., Teo, Jeffrey C. Y., and Louca, Despina. Fri . "Electronic band tuning under pressure in MoTe2 topological semimetal". United States. doi:10.1038/s41535-019-0187-7. https://www.osti.gov/servlets/purl/1561665.
@article{osti_1561665,
title = {Electronic band tuning under pressure in MoTe2 topological semimetal},
author = {Dissanayake, Sachith and Duan, Chunruo and Yang, Junjie and Liu, Jun and Matsuda, Masaaki and Yue, Changming and Schneeloch, John A. and Teo, Jeffrey C. Y. and Louca, Despina},
abstractNote = {Topological superconductors (TSC) can host exotic quasiparticles such as Majorana fermions, poised as the fundamental qubits for quantum computers. TSC’s are predicted to form a superconducting gap in the bulk, and gapless surface/edges states which can lead to the emergence of Majorana zero energy modes. A candidate TSC is the layered dichalcogenide MoTe2, a type-II Weyl (semi)metal in the non-centrosymmetric orthorhombic (Td) phase. It becomes superconducting upon cooling below 0.25 K, while under pressure, superconductivity extends well beyond the structural boundary between the orthorhombic and monoclinic (1T') phases. Here, we show that under pressure, coupled with the electronic band transition across the Td to 1T' phase boundary, evidence for a new phase, we call Td* is observed and appears as the volume fraction of the Td phase decreases in the coexistence region. Td* is most likely centrosymmetric. In the region of space where Td* appears, Weyl nodes are destroyed. Td* disappears upon entering the monoclinic phase as a function of temperature or on approaching the suppression of the orthorhombic phase under pressure above 1 GPa. Our calculations in the orthorhombic phase under pressure show significant band tilting around the Weyl nodes that most likely changes the spin-orbital texture of the electron and hole pockets near the Fermi surface under pressure that may be linked to the observed suppression of magnetoresistance with pressure.},
doi = {10.1038/s41535-019-0187-7},
journal = {npj Quantum Materials},
issn = {2397-4648},
number = 1,
volume = 4,
place = {United States},
year = {2019},
month = {8}
}

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Figures / Tables:

Fig. 1 Fig. 1: Physical properties. a Crystal structure of MoTe2 in the 1T′ phase projected on the ab-plane, with the zigzag chains marked running along the $a$-axis. b Unit cell of the Td structure projected on the ac plane. c Temperature-dependent superconducting (SC) shielding [zero-field-cooled (ZFC)] and Meissner (FC) fraction datamore » for MoTe2 in $H$ = 20 Oe at 1.2 GPa. d Magnetic hysteresis loop for MoTe2 at 2 K at 1.2 GPa. Arrows indicate sweeping direction. e, f Contour map of the neutron scattering intensity obtained by scanning across the (2 0 l) Bragg peak along the [0 0 1] direction at 0.15 GPa on cooling (e) and warming (f). The peak labels denoted with D1 (main domain) and D2 (second domain) are used to distinguish the peaks coming from two different domains, and subscripts 1T′ and Td are used to distinguish the peaks in the different phases. g Temperature dependence of the q integrated neutron scattering intensity for (201) $^{D1}_{1T}$0 peak (red squares), (201) Td peak (blue circles), and (201) Td* (green circles). Arrows indicate sweeping directions. h, i Contour map of the neutron scattering intensity obtained by scanning across the (2 0 l ) Bragg peak along the [0 0 1] direction at 0.95 GPa on cooling (h) and at 1.2 GPa on cooling (i). j The phase diagram under pressure. The region between the two phases shows coexistence of both phases plus the Td* phase. Inversion symmetry is broken only in the Td phase while both Td* and 1T′ are centrosymmetric. k A two-dimensional scan in the h0l plane outside the pressure cell with half-integer peaks from the Td* phase appearing along L. The dashed white lines mark the integer peaks along L that correspond to both the Td and Td* phases while the half-integer peaks belong to the Td* phase only« less

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    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.