Orbital Fingerprint of Topological Fermi Arcs in the Weyl Semimetal TaP

Min, Chul‐Hee; Bentmann, Hendrik; Neu, Jennifer; Eck, Philipp; Moser, Simon; Figgemeier, T.; Ünzelmann, M.; Kißner, K.; Lutz, P.; Koch, Roland; Jozwiak, Chris; Bostwick, Aaron; Rotenberg, Eli; Thomale, Ronny; Sangiovanni, Giorgio; Siegrist, T.; Sante, Domenico Di; Reinert, F.

doi:10.1103/physrevlett.122.116402

Cited by 31 publications

(31 citation statements)

References 44 publications

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“…Weyl semimetals differ from the related Dirac semimetals in that they require either time-reversal or inversion symmetry to be broken in order to lift the degeneracy of the nodes. Consequently, Weyl nodes always exist in pairs of opposite chirality that are connected through Fermi arcs running along the surface of the material, as has been observed experimentally in several materials using angle-resolved photoemission spectroscopy (ARPES) [1][2][3][4][5][6][7]. The chiral nature of the Weyl nodes can furthermore manifest itself in electrical transport, in the form of the chiral anomaly, leading to a negative longitudinal magnetoresistance.…”

Section: Introductionmentioning

confidence: 80%

Two- and Three-Dimensional Superconducting Phases in the Weyl Semimetal TaP at Ambient Pressure

et al. 2020

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The motivation to search for signatures of superconductivity in Weyl semi-metals and other topological phases lies in their potential for hosting exotic phenomena such as nonzero-momentum pairing or the Majorana fermion, a viable candidate for the ultimate realization of a scalable quantum computer. Until now, however, all known reports of superconductivity in type-I Weyl semi-metals have arisen through surface contact with a sharp tip, focused ion-beam surface treatment or the application of high pressures. Here, we demonstrate the observation of superconductivity in single crystals, even an as-grown crystal, of the Weyl semi-metal tantalum phosphide (TaP), at ambient pressure. A superconducting transition temperature, T c , varying between 1.7 and 5.3 K, is observed in different samples, both as-grown and microscopic samples processed with focused ion beam (FIB) etching. Our data show that the superconductivity present in the as-grown crystal is inhomogeneous yet three-dimensional. For samples fabricated with FIB, we observe, in addition to the three-dimensional superconductivity, a second superconducting phase that resides on the sample surface. Through measurements of the characteristic fields as a function of temperature and angle, we are able to confirm the dimensionality of the two distinct superconducting phases.

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Section: Introductionmentioning

confidence: 80%

Two- and Three-Dimensional Superconducting Phases in the Weyl Semimetal TaP at Ambient Pressure

et al. 2020

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“…Until today, angle-resolved photoelectron spectroscopy (ARPES) experiments have confirmed a number of materials as Weyl semimetals (WSM), based on a comparison of the measured bulk band structure to band calculations and the observation of surface Fermi arcs 1 , 9 , 10 , 14 , 15 . Manifestations of the nontrivial topology have also been found, accordingly, in magnetotransport experiments 16 , by scanning tunneling microscopy 17 , and via optically induced photocurrents 18 .…”

Section: Introductionmentioning

confidence: 99%

Momentum-space signatures of Berry flux monopoles in the Weyl semimetal TaAs

Ünzelmann¹,

Bentmann²,

Figgemeier³

et al. 2021

Nat Commun

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Since the early days of Dirac flux quantization, magnetic monopoles have been sought after as a potential corollary of quantized electric charge. As opposed to magnetic monopoles embedded into the theory of electromagnetism, Weyl semimetals (WSM) exhibit Berry flux monopoles in reciprocal parameter space. As a function of crystal momentum, such monopoles locate at the crossing point of spin-polarized bands forming the Weyl cone. Here, we report momentum-resolved spectroscopic signatures of Berry flux monopoles in TaAs as a paradigmatic WSM. We carried out angle-resolved photoelectron spectroscopy at bulk-sensitive soft X-ray energies (SX-ARPES) combined with photoelectron spin detection and circular dichroism. The experiments reveal large spin- and orbital-angular-momentum (SAM and OAM) polarizations of the Weyl-fermion states, resulting from the broken crystalline inversion symmetry in TaAs. Supported by first-principles calculations, our measurements image signatures of a topologically non-trivial winding of the OAM at the Weyl nodes and unveil a chirality-dependent SAM of the Weyl bands. Our results provide directly bulk-sensitive spectroscopic support for the non-trivial band topology in the WSM TaAs, promising to have profound implications for the study of quantum-geometric effects in solids.

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“…Weyl semimetals (WSMs) are the topological phases with broken time-reversal or space-inversion symmetry, whose electronic structure is composed of pairs of Weyl nodes with opposite chirality [1,2]. They are a prototypical representative of the gapless topological materials, and have been experimentally discovered in three-dimensional condensed matters including MoTe 2 , WTe 2 , NbAs, TaP, TaAs, and so forth [3][4][5][6]. WSMs are privileged for many intriguing topographies such as anomalous Hall effect [1,7], surface states with Fermi arcs [4,5], large second harmonic generation [2,8], and circular photogalvanic effect [9,10], etc.…”

Section: Introductionmentioning

confidence: 99%

“…To date, ideal type-I Weyl points with symmetric cone spectra have been ascertained in available semimetals (e.g. NbAs, TaP, TaAs) and also in artificial photonic crystal structures [4][5][6][14][15][16]. In contrast, it was not until 2015 that the concept of type-II WSMs was theoretically proposed by studying the topological properties of WTe 2 and MoTe 2 [13,17].…”

Section: Introductionmentioning

confidence: 99%

Photonic spin Hall effect on the surfaces of type-I and type-II Weyl semimetals

et al. 2020

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Topological optics is an emerging research area in which various topological and geometrical ideas are being proposed to design and manipulate the behaviors of photons. Here, the photonic spin Hall effect on the surfaces of topological Weyl semimetal (WSM) films was studied. Our results show that the spin-dependent splitting (i.e. photonic spin Hall shifts) induced by the spin-orbit interaction is little sensitive to the tilt αt of Weyl nodes and the chemical potential μ in type-I WSM film. In contrast, photonic spin Hall shifts in both the in-plane and transverse directions present versatile dependent behaviors on the αt and μ in type-II WSM film. In particular, the largest in-plane and transverse spin Hall shifts appear at the tilts between −2 and −3, which are ~40 and ~10 times of the incident wavelength, respectively. Nevertheless, the largest spin Hall shifts for type-II WSM film with positive αt are only several times of incident wavelength. Moreover, the photonic spin Hall shifts also exhibit different variation trends with decreasing the chemical potential for different signs of αt in type-II WSM films. This dependence of photonic spin Hall shifts on tilt orientation in type-II WSM films has been explained by time-reversal-symmetry-breaking Hall conductivities in WSMs.

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Orbital Fingerprint of Topological Fermi Arcs in the Weyl Semimetal TaP

Cited by 31 publications

References 44 publications

Two- and Three-Dimensional Superconducting Phases in the Weyl Semimetal TaP at Ambient Pressure

Two- and Three-Dimensional Superconducting Phases in the Weyl Semimetal TaP at Ambient Pressure

Momentum-space signatures of Berry flux monopoles in the Weyl semimetal TaAs

Photonic spin Hall effect on the surfaces of type-I and type-II Weyl semimetals

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