Nontopological origin of the planar Hall effect in the type-II Dirac semimetal NiTe2

Abstract

Dirac and Weyl semimetals are new discovered topological nontrivial materials with the linear band dispersions around the Dirac/Weyl points. When applying non-orthogonal electric current and magnetic field, an exotic phenomenon called chiral anomaly arises and negative longitudinal resistance can be detected. Recently, a new phenomenon named planer Hall effect (PHE) is considered to be another indication of chiral anomaly which has been observed in many topological semimetals. However, it still remains a question that is the PHE only attributed to chiral anomaly?Here we demonstrate the PHE in a new-discovered type-II Dirac semimetal NiTe2 by low temperature transport. However, after detailed analysis, we conclude that the PHE results from the trivial orbital magnetoresistance. This work reveals that PHE is not a sufficient condition of chiral anomaly and one need to take special care of other non-topological contribution in such studies.

Observation of bulk states and spin-polarized topological surface states in transition metal dichalcogenide Dirac semimetal candidate NiTe2

“…In contrast, NiTe 2 has been predicted to host type-II Dirac fermions in vicinity of the Fermi energy [37]. The so far performed experimental studies on NiTe 2 have primarily focused on its crystal structure, and transport properties while its topological band structure remains unexplored [37][38][39][40][41][42][43][44]. Motivated by this, we explored the electronic band structure of NiTe 2 by means of spin-and angle-resolved photoemission spectroscopy (ARPES) in combination with density functional theory (DFT).…”

Strain engineering the topological type-II Dirac semimetal NiTe2

“…Additionally, superconductivity was observed in NiTe 2 under pressure [53] and with the intercalation of Ti into the van der Waals gap (the space between two adjacent chalcogenide layers) [50], and was also predicted in atomically thin systems [54]. Moreover, the energy position of its Dirac node, closer to the Fermi level when compared with similar systems [42,55,56], combined with accessible high-quality single crystals [57][58][59] substantiate the interest on the material.…”

Evidences for pressure-induced two-phase superconductivity and mixed structures of NiTe2 and NiTe in type-II Dirac semimetal NiTe2-x (x = 0.38 ± 0.09) single crystals

“…Other widely studied type-II Dirac/Weyl semimetals include PtTe 2 and PdTe 2 [16,17], although no direct experimental evidence for superconductivity has been reported in these systems. The NiTe 2 system, a type-II Dirac semimetal [18,19], has recently received significant attention because of the observation of various novel phenomena, including linear field dependence of magnetoresistance due to the contribution of Dirac fermions with a Fermi level (E F ) near the Dirac nodes [20,21], and the planar Hall effect due to orbital magnetoresistance [22]. Additionally, theoretical studies have predicted two-gap superconductivity with T c ~ 5.7 K in monolayer NiTe 2 and absence of superconductivity in bulk NiTe 2 [23].…”