Experimental discovery of a topological Weyl semimetal state in TaP

Xu, Su; Belopolski, Ilya; Sanchez, Daniel S.; Chenglong, Zhang; Chang, Guoqing; Guo, Cheng; Bian, Guang; Yuan, Zhujun; Lu, Hong; Chang, Tay Rong; Shibayev, Pavel; Prokopovych, Mykhailo L.; Alidoust, Nasser; Zheng, Hao; Lee, Chi-Cheng; Huang, Shin Ming; Sankar, Raman; Chou, F. C.; Hsu, Chuang‐Han; Jeng, Horng Tay; Bansil, Arun; Neupert, Titus; Strocov, Vladimir N.; Lin, Hsin; Jia, Shuang; Hasan, M. Zahid

doi:10.1126/sciadv.1501092

Cited by 371 publications

(218 citation statements)

References 33 publications

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“…These results are consistent with recent calculations [17,19,20]. Furthermore, recent angle resolved photoemission spectroscopy (ARPES) results [4,5,13,21] show the linear bulk band dispersion across the Weyl points, in agreement with the theoretical calculations. The electronic density of states plot shows a minimum value at the Fermi level.…”

Section: Electronic Structure Calculationssupporting

confidence: 82%

“…Similar properties have also been reported in NbP, with magnetoresistance of 8.5 × 10 4 % at 2 K and 9 T, and mobility of 5 × 10 6 cm 2 ·V −1 ·s −1 [10]. Other transition metal monopnictides that are Weyl semimetals and belong to nonsymmorphic space group I4 1 md are TaP [4] and NbAs [7,11].…”

Section: Introductionsupporting

confidence: 55%

“…A Weyl semimetal is analogous to a 3D version of graphene, since both share similar electronic band dispersion near the Fermi energy. A key property of a Weyl semimetal is that the surface states possesses "Fermi arcs" connecting the projection of bulk nodes in the surface Brillouin zone [4,5].…”

Section: Introductionmentioning

confidence: 99%

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Single Crystal Growth, Resistivity, and Electronic Structure of the Weyl Semimetals NbP and TaP

2016

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Abstract:We have successfully synthesized niobium monophosphide and tantalum monophosphide crystals by a chemical vapor transport technique. We report resistivity vs. temperature of both materials in the temperature range from 2 K to 300 K. We have also performed electronic structure calculations and present the band structure and density of states of these two compounds. The calculations show that both compounds are semimetals, as their conduction and valence bands overlap near the Fermi energy.

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Section: Electronic Structure Calculationssupporting

confidence: 82%

Section: Introductionsupporting

confidence: 55%

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Single Crystal Growth, Resistivity, and Electronic Structure of the Weyl Semimetals NbP and TaP

2016

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mentioning

confidence: 76%

“…Shortly after the prediction, the first, to our knowledge, Weyl semimetal state was experimentally discovered in TaAs via photoemission spectroscopy (30, 31). Later, other photoemission works confirmed the discovery in several members of the TaAs material class (32)(33)(34)(35).In this paper, we propose a new type of Weyl semimetal in an inversion-breaking, stoichiometric compound strontium silicide, SrSi 2 . Our first-principles band structure calculations show that SrSi 2 is already a Weyl semimetal even in the absence of spinorbit coupling.…”

mentioning

confidence: 77%

New type of Weyl semimetal with quadratic double Weyl fermions

Huang

Belopolski

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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359

248

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Weyl semimetals have attracted worldwide attention due to their wide range of exotic properties predicted in theories. The experimental realization had remained elusive for a long time despite much effort. Very recently, the first Weyl semimetal has been discovered in an inversion-breaking, stoichiometric solid TaAs. So far, the TaAs class remains the only Weyl semimetal available in real materials. To facilitate the transition of Weyl semimetals from the realm of purely theoretical interest to the realm of experimental studies and device applications, it is of crucial importance to identify other robust candidates that are experimentally feasible to be realized. In this paper, we propose such a Weyl semimetal candidate in an inversionbreaking, stoichiometric compound strontium silicide, SrSi 2 , with many new and novel properties that are distinct from TaAs. We show that SrSi 2 is a Weyl semimetal even without spin-orbit coupling and that, after the inclusion of spin-orbit coupling, two Weyl fermions stick together forming an exotic double Weyl fermion with quadratic dispersions and a higher chiral charge of ±2. Moreover, we find that the Weyl nodes with opposite charges are located at different energies due to the absence of mirror symmetry in SrSi 2 , paving the way for the realization of the chiral magnetic effect. Our systematic results not only identify a much-needed robust Weyl semimetal candidate but also open the door to new topological Weyl physics that is not possible in TaAs. topological insulator | Weyl fermion | Fermi arc | chiral magnetic effect A nalogous to graphene and the 3D topological insulator, Weyl semimetals are believed to open the next era in condensed matter physics (1-8). A Weyl semimetal represents an elegant example of the correspondence between condensed matter and high-energy physics because its low-energy excitations, the Weyl fermions, are massless particles that have played an important role in quantum field theory and the standard model but have not been observed as a fundamental particle in nature. A Weyl semimetal is also a topologically nontrivial metallic phase of matter extending the classification of topological phases beyond insulators (3-6). The nontrivial topological nature guarantees the existence of exotic Fermi arc electron states on the surface of a Weyl semimetal. In contrast with a topological insulator where the bulk is gapped and only the Dirac cones on its surfaces are of interest, in a Weyl semimetal, both the Weyl fermions in the bulk and the Fermi arcs on the surface are fundamentally new and are expected to give rise to a wide range of exotic phenomena (9-22).For many years, research on Weyl semimetals has been held back due to the lack of experimentally feasible candidate materials. Early theoretical proposals require either magnetic ordering in sufficiently large domains (3, 23-26) or fine-tuning of the chemical composition to within 5% in an alloy (23,(25)(26)(27), which proved demanding in real experiments. Recently, our group and a concurrent group s...

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Detection of Nontrivial Topology Driven by Charge Density Wave in a Semi‐Dirac Metal

Alam,

Boyal,

Roy

et al. 2023

Adv Funct Materials

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The presence of electron correlations in a system with topological order can lead to exotic ground states. Considering single crystals of LaAgSb2 which has a square net crystal structure, one finds multiple charge density wave transitions (CDW) as the temperature is lowered. Large planar Hall (PHE) signals are found in the CDW phase, which are still finite in the high‐temperature phase though they change sign. Optimizing the structure within first‐principles calculations, one finds an unusual chiral metallic phase. This is because as the temperature is lowered, the separation between the Ag/Sb atoms on different layers decreases, leading to stronger repulsions between electrons associated with atoms on different layers. This leads to successive layers sliding with respect to each other, thereby stabilizing a chiral structure in which inversion symmetry is also broken. The large Berry curvature associated with the low‐temperature structure explains the low‐temperature PHE. At high temperature, the PHE arises from the changes induced in the anisotropic Dirac cone in presence of a magnetic field. This work represents a route toward detecting and understanding the mechanism in a correlation‐driven topological transition through electron transport measurements, complemented by ab‐initio electronic structure calculations.

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Experimental discovery of a topological Weyl semimetal state in TaP

Abstract: Photoemission established tantalum phosphide as a Weyl semimetal, which hosts exotic Weyl fermion quasiparticles and Fermi arcs.

Cited by 371 publications

References 33 publications

Single Crystal Growth, Resistivity, and Electronic Structure of the Weyl Semimetals NbP and TaP

Single Crystal Growth, Resistivity, and Electronic Structure of the Weyl Semimetals NbP and TaP

New type of Weyl semimetal with quadratic double Weyl fermions

Detection of Nontrivial Topology Driven by Charge Density Wave in a Semi‐Dirac Metal

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