Topological semimetals with triply degenerate nodal points in θ -phase tantalum nitride

By H. Weng, Chen Fang, Z. Fang, X. Dai. 2016

224 citations recorded by the source corpus.

Using first-principles calculation and symmetry analysis, we propose that $\ensuremath{\theta}$-TaN is a topological semimetal having a new type of point nodes, i.e., triply degenerate nodal points. Each node is a band crossing between degenerate and nondegenerate bands along the high-symmetry line in the Brillouin zone, and is protected by crystalline symmetries. Such new type of nodes will always generate singular touching points between different Fermi surfaces and three-dimensional spin texture around them. Breaking the crystalline symmetry by external magnetic field or strain leads to various topological phases. By studying the Landau levels under a small field along the $c$ axis, we demonstrate that the system has a new quantum anomaly that we call ``helical anomaly.'

Subfields: Atomic and Molecular Physics, and Optics, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/ff23e6095a68f445839df0ac456b360a05d6f6af

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In Atomic and Molecular Physics, and Optics

In Materials Chemistry

Citations in the corpus

Triple Point Topological Metals (2016, background): “[57] appeared, discussing some of the topological properties of TaN—one of the materials we propose for type-A triple points in this work.”
Weyl and Dirac semimetals in three-dimensional solids (2017, methodology): “The space of candidate DSMs produced by band inversion is enlarged by considering ternary compounds (Du et al., 2015; Gibson et al., 2015; Kariyado and Ogata, 2011; Sklyadneva et al., 2016; Weng et al., 2016a).”
Topological Semimetals from First Principles (2018, background): “The first proposals for observing this new type of TSM in real materials were focused on a family of two-element metals AB with tungsten carbide (WC) structure, where A = {Zr,Nb,Mo,Ta,W} and B = {C,N,P, S,Te} (14, 15, 16).”