Ca 3 P 2 and other topological semimetals with line nodes and drumhead surface states

By Y. Chan, Ching-Kai Chiu, M. Chou, A. Schnyder. 2015

265 citations recorded by the source corpus.

Topological nodal line semimetals exhibit protected one-dimensional Fermi lines, which arise due to an intricate interplay between the symmetry and topology of the electronic wave functions. In this paper, the authors derive the $\mathbb{Z}$ invariants that guarantee the stability of the line nodes in the bulk under reflection symmetry and show that a quantized Berry phase (i.e, a ${\mathbb{Z}}_{2}$ invariant) leads to the appearance of protected surfaces states, which take the shape of a drumhead. Most importantly, a relation between the $\mathbb{Z}$ invariant, which characterizes the bulk, and the quantized Berry phase is derived. This relation is generally applicable to any topological nodal line semimetal with or without spin-orbit coupling. Moreover, it is shown that the Berry phase invariant can be simply obtained by computing the reflection parity eigenvalues. As a representative example of a topological nodal line semimetal, the authors examine Ca${}_{3}$P${}_{2}$, which has been identified as an ideal system with the line nodes at the Fermi energy. Using numerical calculations, they show that the drumhead surface state of Ca${}_{3}$P${}_{2}$ has a rather weak dispersion, which implies that correlation effects are enhanced at the surface.

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

View Paper: https://www.semanticscholar.org/paper/b6d8a14edf5ce3ae8aa0de22fc017335de1e396b

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In Atomic and Molecular Physics, and Optics

In Materials Chemistry

Citations in the corpus

Triple Point Topological Metals (2016, background): “nodal lines with nontrivial Berry phase, as is the case for type B, is generally associated with the appearance of surface states [26,27].”
Beyond Dirac and Weyl fermions: Unconventional quasiparticles in conventional crystals (2016, background): “However, the nontrivial Berry phase associated with the line node in SG 220 implies the presence of a “Fermi drum ” surface state (33, 43), although this will not be robust to breaking of the crystal symmetry in the bulk.”
Nodal-knot semimetals (2017, background): “There are quite a few material candidates of nodal lines: Cu3NPd and Cu3NZn[39, 40], calcium phosphide[52, 53], carbon networks[37], CaP3[54], alkali earth materials[55, 56], to name a few.”