Anomalous electronic structure and magnetoresistance in TaAs2

Luo, Yongkang; McDonald, R. D.; Rosa, P. F. S.; Scott, Brian L.; Wakeham, N.; Ghimire, Nirmal; Bauer, E. D.; Thompson, J. D.; Ronning, F.

doi:10.1038/srep27294

Cited by 90 publications

(95 citation statements)

References 49 publications

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“…Negative magnetoresistance has been observed experimentally for NbAs 2 [17,18], TaAs 2 [17] and TaSb 2 [17,20]. Anomalous, albeit not negative, magnetoresistance has been observed for NbSb 2 [12] and TaAs 2 [15]. However, there are also experiments which point to the opposite, which is that there is no negative magnetoresistance in these materials.…”

Section: Introductionmentioning

confidence: 99%

“…This effect could be of help in the search for an explanation of the anomalous magnetoresistance in these materials. Recently, transition metal dipnictides of the type AB 2 (A ä{Ta, Nb}, B ä{As, Sb}) have gained a lot of attention [12][13][14][15][16][17][18][19] for their giant magnetoresistance. These materials are semimetals, but without a direct closure of the band gap.…”

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confidence: 99%

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Hidden Weyl points in centrosymmetric paramagnetic metals

Gresch

Winkler

et al. 2017

New J. Phys.

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The transition metal dipnictides TaAs2, TaSb2, NbAs2 and NbSb2 have recently sparked interest for exhibiting giant magnetoresistance. While the exact nature of magnetoresistance in these materials is still under active investigation, there are experimental results indicating anisotropic negative magnetoresistance. We study the effect of magnetic field on the band structure topology of these materials by applying a Zeeman splitting. In the absence of magnetic field, we find that the materials are weak topological insulators, which is in agreement with previous studies. When the magnetic field is applied, we find that type -II Weyl points form. This result is found first from a symmetry argument, and then numerically for a k • p model of TaAs2 and a tight-binding model of NbSb2. This effect can be of help in search for an explanation of the anomalous magnetoresistance in these materials.

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Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Hidden Weyl points in centrosymmetric paramagnetic metals

Gresch

Winkler

et al. 2017

New J. Phys.

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“…However, a negative longitudinal MR was also observed in other materials: semimetals without Weyl nodes near the Fermi energy, e.g. in MPn 2 (M=Nb, Ta; Pn=As, Sb) [34][35][36][37], the zero band-gap semiconductor GdPtBi [38], and in layered metals with a large quasi twodimensional Fermi surface, such as the highly conductive delafossites PdCoO 2 and PtCoO 2 and the ruthenate Sr 2 RuO 4 [39]. In all these materials a magnetic field induces a strong enhancement of the resistance anisotropy r r = A xx zz .…”

Section: Introductionmentioning

confidence: 99%

On the search for the chiral anomaly in Weyl semimetals: the negative longitudinal magnetoresistance

et al. 2016

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Recently, the existence of massless chiral (Weyl) fermions has been postulated in a class of semi-metals with a non-trivial energy dispersion. These materials are now commonly dubbed Weyl semi-metals (WSM). One predicted property of Weyl fermions is the chiral or Adler-Bell-Jackiw anomaly, a chirality imbalance in the presence of parallel magnetic and electric fields. In WSM, it is expected to induce a negative longitudinal magnetoresistance (MR). Here, we present experimental evidence that the observation of the chiral anomaly can be hindered by an effect called 'current jetting'. This effect also leads to a strong apparent negative longitudinal MR, but it is characterized by a highly non-uniform current distribution inside the sample. It appears in materials possessing a large field-induced anisotropy of the resistivity tensor, such as almost compensated high-mobility semimetals due to the orbital effect. In case of a non-homogeneous current injection, the potential distribution is strongly distorted in the sample. As a consequence, an experimentally measured potential difference is not proportional to the intrinsic resistance. Our results on the MR of the Weyl semimetal candidate materials NbP, NbAs, TaAs, and TaP exhibit distinct signatures of an inhomogeneous current distribution, such as a field-induced 'zero resistance' and a strong dependence of the 'measured resistance' on the position, shape, and type of the voltage and current contacts on the sample. A misalignment between the current and the magneticfield directions can even induce a 'negative resistance'. Finite-element simulations of the potential distribution inside the sample, using typical resistance anisotropies, are in good agreement with the experimental findings. Our study demonstrates that great care must be taken before interpreting measurements of a negative longitudinal MR as evidence for the chiral anomaly in putative Weyl semimetals.

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“…The calculation also shows that Nb(Ta)As 2 and NbSb 2 are close to the compensated semimetals with equal electron and hole densities. Both the electron and hole bands are weakly topological, leading to a fragile surface state [57].…”

Section: Bulk and Surface Electron Statesmentioning

confidence: 99%

“…Luo et al reported that the LMR of TaAs 2 reaches an extremely large number (−98%) in 3 T at 2 K, which persists up to 150 K [57] [ Fig. 8(d)].…”

Section: Negative Longitudinal Magnetoresistancementioning

confidence: 99%

Crystal growth and electrical transport properties of niobium and tantalum monopnictide and dipnictide semimetals

Jia

2017

Front. Phys.

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The discovery of the first Weyl semimetal tantalum monoarsenide has greatly promoted physical research on the niobium and tantalum pnictide compounds. Crystallizing into the NbAs-and OsGe 2 -type structures, these mono-and di-pnictide semimetals manifest exotic electrical transport properties in magnetic field, which only occur in their single-crystalline forms. All the unusual electrical properties correspond to their poor carriers, which are indeed vulnerable to various crystal defects. In this review article, we present a comprehensive comparison of the crystal growth and electrical transport properties of the two semimetal families. We then discuss in detail the possible characteristic transport features, such as the chiral anomaly of Weyl quasiparticles. We emphasize the importance of crystal growth and sample manipulation for exploring the unique topological properties of Weyl semimetals in the future.

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Anomalous electronic structure and magnetoresistance in TaAs2

Cited by 90 publications

References 49 publications

Hidden Weyl points in centrosymmetric paramagnetic metals

Hidden Weyl points in centrosymmetric paramagnetic metals

On the search for the chiral anomaly in Weyl semimetals: the negative longitudinal magnetoresistance

Crystal growth and electrical transport properties of niobium and tantalum monopnictide and dipnictide semimetals

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