Direct observation of nonequivalent Fermi-arc states of opposite surfaces in the noncentrosymmetric Weyl semimetal NbP

Souma, S.; Wang, Zhiwei; Kotaka, Hiroki; Sato, Takafumi; Nakayama, K.; Tanaka, Yukio; Kobayashi, Hideo; Takahashi, Takashi; Yamauchi, Kunihiko; Oguchi, Tamio; Segawa, Kouji; Ando, Yoichi

doi:10.1103/physrevb.93.161112

Cited by 105 publications

(125 citation statements)

References 40 publications

Supporting

Mentioning

111

Contrasting

Order By: Relevance

“…Our results for TaP and NbP reveal a universal evolution of the Fermi arc surface states, and demonstrate that these states disperse over a much larger energy range, compared to the energy range of the existence of Weyl fermion quasiparticles. For this reason, Fermi arcs can be observed in compounds such as NbP [40,41], even when there are no Weyl fermion quasiparticles and associated magnetotransport phenomena [45,46].…”

Section: Pagementioning

confidence: 99%

“…On the other hand, although the Fermi arcs, which are one of the spectroscopic hallmarks of a WSM, are observed in all members of the transition-metal monopnictide family at both pnictogen- [34,[36][37][38][39][40] and metalterminated [35,41] surfaces, the magnetotransport behaviors related to the chiral anomaly effect are distinct among the different compounds. The negative longitudinal MR, which has a maximum value of -30% at ~6 T in TaAs [42] and as large as -3000% at 9T in TaP without any sign of saturation [43,44], has never been observed in NbP [45,46].…”

Section: Pagementioning

confidence: 99%

“…1a-c [35,41] surfaces, the magnetotransport behaviors related to the chiral anomaly effect are distinct among the different compounds. The negative longitudinal MR, which has a maximum value of -30% at ~6 T in TaAs [42] and as large as -3000% at 9T in TaP without any sign of saturation [43,44], has never been observed in NbP [45,46].…”

mentioning

confidence: 99%

See 2 more Smart Citations

Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals

Autès

Matt

et al. 2017

Phys. Rev. Lett.

View full text Add to dashboard Cite

Although any evidence of chiral Weyl fermions as fundamental particles in vacuum is still lacking, recent advances in topological condensed matter physics [1,2] provide a new way of realizing them in Weyl semimetals (WSMs). In an ideal WSM, bands without spin degeneracy cross at pairs of points at the Fermi level, the Weyl nodes, and the corresponding low-energy excitations fulfill the Weyl equation [3,4].As a consequence, the quasiparticles in a WSM show the same exotic behaviors as Weyl fermions, such as the chiral anomaly effect [5][6][7] that can induce a negative longitudinal magneto-resistance (MR). Another hallmark of a WSM is the existence of anomalous surface states protected by the bulk band topology, the so-called Fermi arcs [8,9]. The WSM state has been proposed in magnetic systems [8,[10][11][12][13][14][15][16][17][18][19], Dirac semimetals [20][21][22][23][24][25][26][27] under magnetic field [28], as well as photonic crystals [29,30].Recently, non-magnetic transition-metal monopnictides with broken inversion symmetry (the crystal structure and the first Brillouin zone (BZ) of these materials are shown in Fig. 1a-c [35,41] surfaces, the magnetotransport behaviors related to the chiral anomaly effect are distinct among the different compounds. The negative longitudinal MR, which has a maximum value of -30% at ~6 T in TaAs [42] and as large as -3000% at 9T in TaP without any sign of saturation [43,44], has never been observed in NbP [45,46]. The apparent disagreement between the transport and spectroscopic signatures of WSM raises the questions of whether the observation of topological Fermi arcs is sufficient to identify a WSM phase [38,47], and whether the negative longitudinal MR in transition-metal monopnictides is not induced by the chiral anomaly but rather by the axial anomaly effect, which is not related to the Weyl fermion quasiparticles [48].Here, we present a comparative study of transition-metal monopnictides by Polycrystalline NbP (TaP) was synthesized by a solid-state reaction using elemental niobium (tantalum) and red phosphorus with a minimum purity of 99.99 %. The respective amounts of starting reagents were mixed and pressed into pellets in a Heglove box and annealed in an evacuated quartz ampule at 1050 °C for 60 hours.Laboratory x-ray diffraction measurements, which were done at room temperature using Cu Ka radiation on a Brucker D8 diffractometer, have shown that the obtained crystals are single phase with the tetragonal structure of space group I41/amd (N 141).Clean surfaces for ARPES measurements were obtained by cleaving NbP and TaP samples in a vacuum better than 5 × 10 -11 Torr. Surface-sensitive VUV-ARPES measurements were performed with circular-polarized light at the Surface/Interface Spectroscopy (SIS) beamline at the Swiss Light Source (SLS) with a Scienta R4000.Bulk-sensitive soft X-ray ARPES measurements were performed at the Advanced Resonant Spectroscopies (ADRESS) beamline at SLS [49] using a SPECS analyser, and data were collected using circular-polarized light w...

show abstract

Section: Pagementioning

confidence: 99%

Section: Pagementioning

confidence: 99%

See 1 more Smart Citation

Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals

Autès

Matt

et al. 2017

Phys. Rev. Lett.

View full text Add to dashboard Cite

show abstract

“…In non-centrosymmetric Weyl semimetals, different patterns of Fermi arcs on the top and bottom surfaces are theoretically expected [36,37]. Indeed, an ARPES study on NbP [38] revealed the nonequivalent forms of Fermi arcs on respective surfaces, that are terminated at the same 2D projected bulk Weyl nodes. Also for MoTe2, the difference of the surface states and Fermi arcs for both terminations are discussed in comparison with calculations [22,27].…”

mentioning

confidence: 99%

Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe2

et al. 2017

View full text Add to dashboard Cite

We investigate the surface electronic structures of polar 1T'-MoTe2, the Weyl semimetal candidate realized through the nonpolar-polar structural phase transition, by utilizing the laser angle-resolved photoemission spectroscopy combined with first-principles calculations. Two kinds of domains with different surface band dispersions are observed from a single-crystalline sample. The spin-resolved measurements further reveal that the spin polarizations of the surface and the bulk-derived states show the different domain-dependences, indicating the opposite bulk polarity. For both domains, some segment-like band features resembling the Fermi arcs are clearly observed. The patterns of the arcs present the marked contrast between the two domains, respectively agreeing well with the slab calculation of (0 0 1) and (0 0 -1) surfaces. The present result strongly suggests that the Fermi arc connects the identical pair of Weyl nodes on one side of the polar crystal surface, whereas it connects between the different pairs of Weyl nodes on the other side. Weyl nodes) at the Fermi level (EF). The bulk electronic structure of Weyl semimetals is characterized by the spin-polarized Weyl cone dispersions formed through the breaking of either time-reversal or space-inversion symmetry [1][2][3][4]. At the surface, on the other hand, the chiral charge associated with the Weyl nodes warrants the existence of the gapless surface states, socalled Fermi arcs that connect the two-dimensionally (2D) projected Weyl nodes. Due to these unusual bulk and surface electronic states, a variety of new magnetoelectric phenomena have been predicted [4][5][6][7][8][9]. Until now, several experimental verifications of realistic Weyl semimetal compounds have been raised (eg. the TaAs family [10][11][12] The single-crystalline 1T'-MoTe2 was synthesized as reported elsewhere [19,20].ARPES at 25 K was performed using the He-discharge lamp (21.2 eV) and the fourth harmonic generation of Ti:sapphire laser (6.43 eV, s-polarized light) [28], with a VG-Scienta R4000WALanalyzer. The total energy resolution was set to 10 and 3 meV, respectively. For the laser-SARPES at 25 K and the ARPES at 100 K, a 6.99 eV laser (s-polarized light) and a ScientaOmicron DA30Lanalyzer mounted with two sets of very-low-energy electron diffraction spin detectors were used at the Institute of Solid State Physics (ISSP), The University of Tokyo [29]. The total energy resolution was set to 30 and 3 meV, respectively. Samples were cleaved in situ at room temperature. All measurements were performed in ultrahigh vacuum better than 1×10 -10 Torr.Electronic structure calculations were performed within the context of density functional theory (DFT) using the Perdew-Burke-Ernzerhof exchange-correlation functional as implemented in the VASP program [30,31]. Relativistic effects were fully included. The structure parameters in Ref.[14] were used, and the corresponding Brillouin zone was sampled by a 20 × 10 × 5 k-mesh. To focus on the near-EF electronic structure, the ARPES images...

show abstract

“…The existence of three-dimensional (3D) Dirac semimetals was first confirmed by angle-resolved photoemission spectroscopy (ARPES) of Cd 3 As 2 [9, 10] and Na 3 Bi [11], where the VB and CB contact each other at the point (Dirac point) protected by rotational symmetry of the crystal [12,13]. Recent ARPES studies on noncentrosymmetric transition-metal monopnictides [14][15][16][17] have clarified pairs of bulk Dirac-cone bands and Fermi-arc SSs, supporting their Weyl-semimetallic nature [18,19]. While the existence of Weyl semimetals with point nodes has been confirmed experimentally, the experimental studies of LNSMs with line nodes are relatively scarce [20][21][22][23] despite many theoretical predictions [24][25][26][27][28][29][30].…”

mentioning

confidence: 99%

Dirac-node arc in the topological line-node semimetal HfSiS

Takane¹,

Wang²,

Souma³

et al. 2016

Phys. Rev. B

Self Cite

163

134

View full text Add to dashboard Cite

We have performed angle-resolved photoemission spectroscopy on HfSiS, which has been predicted to be a topological line-node semimetal with square Si lattice. We found a quasi-two-dimensional Fermi surface hosting bulk nodal lines, alongside the surface states at the Brillouin-zone corner exhibiting a sizable Rashba splitting and band-mass renormalization due to many-body interactions. Most notably, we discovered an unexpected Dirac-like dispersion extending one-dimensionally in k space -the Dirac-node arc -near the bulk node at the zone diagonal. These novel Dirac states reside on the surface and could be related to hybridizations of bulk states, but currently we have no explanation for its origin. This discovery poses an intriguing challenge to the theoretical understanding of topological line-node semimetals. In contrast to conventional semimetals with a finite band-overlap between valence band (VB) and conduction band (CB), topological semimetals are categorized by the band-contacting nature between VB and CB in the Brillouin zone (BZ); point-contact (Dirac/Weyl semimetals) or line-contact (line-node semimetals; LNSMs). The existence of three-dimensional (3D) Dirac semimetals was first confirmed by angle-resolved photoemission spectroscopy (ARPES) of Cd 3 As 2 [9, 10] and Na 3 Bi [11], where the VB and CB contact each other at the point (Dirac point) protected by rotational symmetry of the crystal [12,13]. Recent ARPES studies on noncentrosymmetric transition-metal monopnictides [14][15][16][17] have clarified pairs of bulk Dirac-cone bands and Fermi-arc SSs, supporting their Weyl-semimetallic nature [18,19]. While the existence of Weyl semimetals with point nodes has been confirmed experimentally, the experimental studies of LNSMs with line nodes are relatively scarce [20][21][22][23] despite many theoretical predictions [24][25][26][27][28][29][30].Recently, it was theoretically proposed by Xu et al. that ZrSiO with PbFCl-type crystal structure (space group P 4/nmm) and its isostructural family WHM (W = Zr, Hf, or La; H = Si, Ge, Sn, or Sb; M = O, S, Se and Te; see Fig. 1 . These studies demonstrated the realization of LNSM phase as well as an appearance of nearly-flat SSs around theX point, both were explained on the basis of band calculations.In this Letter, we report the ARPES results on HfSiS. In addition to the overall VB structure which is in support of the LNSM nature of HfSiS, we found new spectral features, such as a large Rashba splitting of SSs atX, a dispersion kink at ∼0.05 eV, and most importantly, unexpected Dirac-like SSs forming a "Dirac-node arc". This is a rare case in the research of topological materials that experiment finds novel SSs that were not predicted by theory.Figure 1(c) shows the ARPES-intensity plot in the VB region as a function of wave vector and binding energy (E B ) measured along theΓX cut at hν = 80 eV (see Supplemental Materials for details of sample preparation [33] and ARPES measurements). One can notice several dispersive bands; holelike bands atΓ (h) with the to...

show abstract

Direct observation of nonequivalent Fermi-arc states of opposite surfaces in the noncentrosymmetric Weyl semimetal NbP

Cited by 105 publications

References 40 publications

Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals

Distinct Evolutions of Weyl Fermion Quasiparticles and Fermi Arcs with Bulk Band Topology in Weyl Semimetals

Observation of spin-polarized bands and domain-dependent Fermi arcs in polar Weyl semimetal MoTe2

Dirac-node arc in the topological line-node semimetal HfSiS

Contact Info

Product

Resources

About