Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe
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Guan, Syu‐You; Chen, Peng‐Jen; Chu, Ming‐Wen; Sankar, Raman; Chou, F. C.; Jeng, Horng‐Tay; Chang, Chia-Seng; Chuang, Tien-Ming

doi:10.1126/sciadv.1600894

Cited by 167 publications

(107 citation statements)

References 61 publications

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“…While our data alone cannot distinguish the isotropic 2-gap state from such a mixed state, comparison with data from other groups makes the fully gapped state most likely. STM measurements show fully gapped superconductivity 31 , while thermal conductivity 30 and H C2 measurments 29 are both consistent with multiple fully gapped bands. This picture also matches the theoretical expectations of Samokhin et al 18 where a noncentrosymmetric superconductor with pairing caused by phonons should exhibit two-band nodeless superconductivity.…”

Section: Resultsmentioning

confidence: 64%

“…Furthermore, thermal conductivity measurements are consistent with fully gapped superconductivity as there is no linear term at low temperature, and the field dependence suggests multi-band superconductivity 30 . STM 31 and ARPES 32 results support this multi-band picture as they both show multiple relevant bands near the Fermi surface. However, despite this broad agreement, tunnel diode oscillator measurements of the penetration depth were found to be consistent with single-band swave superconductivity 33 .…”

Section: Introductionmentioning

confidence: 66%

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μSR study of the noncentrosymmetric superconductor PbTaSe2

et al. 2017

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We present muon spin rotation and relaxation (µSR) measurements on the noncentrosymmetric superconductor PbTaSe2. From measurements in an applied transverse field between Hc1 and Hc2, we extract the superfluid density as a function of temperature in the vortex state. This data can be fit with a fully gapped two-band model, consistent with previous evidence from ARPES, thermal conductivity, and resistivity. Furthermore, zero field measurements show no evidence for a time reversal symmetry breaking field greater than 0.05 G in the superconducting state. This makes exotic fully gapped spin-triplet states unlikely, and hence we contend that PbTaSe2 is characterized by conventional BCS s-wave superconductivity in multiple bands.

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Section: Resultsmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 66%

μSR study of the noncentrosymmetric superconductor PbTaSe2

et al. 2017

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“…However, the natural occurrence of TSC is extremely scarce with the unique promising candidate being Sr 2 RuO 4 for its spin-triplet pairing, 21 despite that a wide range of candidate materials have been proposed. [22][23][24][25] To date, two viable avenues to access TSC have been demonstrated, i.e., either doping or pressurizing TI, TDS, and TWS. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] However, the topologically nontrivial nature of the doping-and pressure-induced superconductivity is under heavy debate yet.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced superconductivity in MoP

Chi

Chen

et al. 2018

npj Quant Mater

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Topological semimetal, a novel state of quantum matter hosting exotic emergent quantum phenomena dictated by the nontrivial band topology, has emerged as a new frontier in condensed-matter physics. Very recently, the coexistence of triply degenerate points of band crossing and Weyl points near the Fermi level was theoretically predicted and experimentally identified in MoP. Via high-pressure electrical transport measurements, we report here the emergence of pressure-induced superconductivity in MoP with a critical transition temperature T c of ca. 2.5 K at ca. 30 GPa. No structural phase transition is observed up to ca. 60 GPa via synchrotron X-ray diffraction study. Accordingly, the topologically nontrivial band protected by the crystal structure symmetries and superconductivity are expected to coexist at pressures above 30 GPa, consistent with density functional theory calculations. Thus, the pressurized MoP represents a promising candidate of topological superconductor. Our finding is expected to stimulate further exploitation of exotic emergent quantum phenomena in novel unconventional fermion system. npj Quantum Materials (2018) 3:28 ; doi:10.1038/s41535-018-0102-7 INTRODUCTIONThe low-energy, long-wavelength quasiparticle excitation near the Fermi level as counterpart of high-energy relativistic Dirac, Weyl, and Majorana fermion has been successfully demonstrated in topological quantum matter with nontrivial band topology such as topological insulator (TI), topological Dirac semimetal (TDS), topological Weyl semimetal (TWS), and topological superconductor (TSC) over the last decade. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] In stark contrast with the gapped bulk state of both TI and TSC, the defining hallmark of TDS and TWS is the presence of linear crossing points of conduction band and valence band near the Fermi level, where two or four bands are exactly degenerate at certain momentum-energy value in the first Brillouin zone, giving rise to a gapless bulk state. Novel macroscopic quantum phenomena they exhibit such as ultrahigh mobility of charge carriers, extremely large linear magnetoresistance, quantum anomalous Hall effect, and chiral anomaly are not only of fundamental interest but also hold potential applications. The recent breakthrough in predicting and identifying unconventional "new fermion" beyond conventional Dirac and Weyl fermion sparked new research interest in the field of topological semimetal. [15][16][17][18][19][20] Among the symmetries of 230 crystal space groups in condensed-matter physics, the threefold, sixfold, and eightfold degenerate quasiparticle excitation emanating from the multiply degenerate points of band crossing near the Fermi level can be protected in a crystal lattice either by symmorphic rotation combined with mirror symmetries or by non-symmorphic

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“…The absence of inversion symmetry in NCS materials introduces an antisymmetric spin-orbit coupling [4,5] which can result in a splitting of the spin-up and spin-down conduction electron energy bands. This splitting of the Fermi surface, lifting the degeneracy of the conduction electrons, may result in a superconducting pair wave function that is an admixture of spin-singlet and spin-triplet states, although there are several examples of NCS superconductors where it has been established that the order parameter is not unconventional, for example, BiPd [6] and PbTaSe 2 [7]. Singlet-triplet mixing can lead NCS materials to display significantly different properties from conventional superconducting systems, for example, the triplet pairing seen in Li 2 (Pd,Pt) 3 Si [8][9][10][11], and upper critical fields close to or exceeding the Pauli limiting field observed in Mo 3 Al 2 C [3,12] Re 3 W [13], Ca(Ir, Pt)Si 3 [14], Li 2 (Pd,Pt) 3 Si [8][9][10][11], LaRhSi 3 [15], Nb 0.…”

Section: Introductionmentioning

confidence: 99%

Superconducting and normal-state properties of the noncentrosymmetric superconductorRe6Zr

et al. 2017

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We systematically investigate the normal and superconducting properties of noncentrosymmetric Re 6 Zr using magnetization, heat capacity, and electrical resistivity measurements. Resistivity measurements indicate Re 6 Zr has poor metallic behavior and is dominated by disorder. Re 6 Zr undergoes a superconducting transition at T c = (6.75 ± 0.05) K. Magnetization measurements give a lower critical field, μ 0 H c1 = (10.3 ± 0.1) mT. The Werthamer-Helfand-Hohenberg model is used to approximate the upper critical field μ 0 H c2 = (11.2 ± 0.2) T, which is close to the Pauli limiting field of 12.35 T and which could indicate singlet-triplet mixing. However, low-temperature specific-heat data suggest that Re 6 Zr is an isotropic, fully gapped s-wave superconductor with enhanced electron-phonon coupling. Unusual flux pinning resulting in a peak effect is observed in the magnetization data, indicating an unconventional vortex state.

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Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe ₂

Abstract: Topological surface states in PbTaSe2 show fully gapped superconductivity, making it a potential topological superconductor.

Cited by 167 publications

References 61 publications

μSR study of the noncentrosymmetric superconductor PbTaSe2

μSR study of the noncentrosymmetric superconductor PbTaSe2

Pressure-induced superconductivity in MoP

Superconducting and normal-state properties of the noncentrosymmetric superconductorRe6Zr

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Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe 2

Abstract: Topological surface states in PbTaSe2 show fully gapped superconductivity, making it a potential topological superconductor.

Cited by 167 publications

References 61 publications

μSR study of the noncentrosymmetric superconductor PbTaSe2

μSR study of the noncentrosymmetric superconductor PbTaSe2

Pressure-induced superconductivity in MoP

Superconducting and normal-state properties of the noncentrosymmetric superconductorRe6Zr

Contact Info

Product

Resources

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Superconducting topological surface states in the noncentrosymmetric bulk superconductor PbTaSe ₂