Quantum oscillations of electrical resistivity in an insulator
Science (2018)
Abstract:
© The Authors, some rights reserved. In metals, orbital motions of conduction electrons on the Fermi surface are quantized in magnetic fields, which is manifested by quantum oscillations in electrical resistivity. This Landau quantization is generally absent in insulators. Here we report a notable exception in an insulator — ytterbium dodecaboride (YbBi2>. The resistivity of YbBi2, which is of a much larger magnitude than the resistivity in metals, exhibits distinct quantum oscillations. These unconventional oscillations arise from the insulating bulk, even though the temperature dependence of the oscillation amplitude follows the conventional Fermi liquid theory of metals with a large effective mass. Quantum oscillations in the magnetic torque are also observed, albeit with a lighter effective mass.Measurement of the bulk and surface bands in Dirac line-node semimetal ZrSiS* * Project supported by the National Key R&D Program of China (Grant No. 2017YFA0305400), Chinese Academy of Science–Shanghai Science Research Center (Grant No. CAS-SSRC-YH-2015-01), the National Natural Science Foundation of China (Grant No. 11674229), the Engineering and Physical Sciences Research Council Platform (Grant No. EP/M020517/1), and the Hefei Science–Center Chinese Academy of Sciences (Grant No. 2015HSC-UE013).
Chinese Physics B IOP Publishing 27:1 (2018) 017105
How to probe the spin contribution to momentum relaxation in topological insulators (vol 8, 2017)
NATURE COMMUNICATIONS 9 (2018) ARTN 729
Topological origin of the type-II Dirac fermions in PtSe2
Physical Review Materials American Physical Society 1:7 (2017)
Abstract:
Group VIII transition-metal dichalcogenides have recently been proposed to host type-II Dirac fermions. They are Lorentz-violating quasiparticles marked by a strongly tilted conic dispersion along a certain momentum direction and therefore have no analogs in the standard model. Using high-resolution angle-resolved photoemission spectroscopy, we systematically studied the electronic structure of PtSe2 in the full three-dimensional Brillouin zone. As predicted, a pair of type-II Dirac crossings is experimentally confirmed along the kz axis. Interestingly, we observed conic surface states around time-reversal-invariant momenta Γ and M points. The signatures of nontrivial topology are confirmed by the first-principles calculation, which shows an intricate parity inversion of bulk states. Our discoveries not only contribute to a better understanding of topological band structure in PtSe2 but also help further explore the exotic properties, as well as potential application, of group VIII transition-metal dichalcogenides.Lifshitz Transitions Induced by Temperature and Surface Doping in Type‐II Weyl Semimetal Candidate Td‐WTe2
physica status solidi (RRL) - Rapid Research Letters Wiley 11:12 (2017)