Nodal-knot semimetals

Nodal-link semimetals

Topological phases of matter have been among the most active research subjects in condensed matter physics. They can be broadly classified as two major classes. The first class of phases, including topological insulators and superconductors[1–6], and other symmetry protected topological phases[7], have gapped bulks with nontrivial topological structures characterized by topological invariants[8...

Topological Semimetals carrying Arbitrary Hopf Numbers: Hopf-Link, Solomon’s-Knot, Trefoil-Knot and Other Semimetals

We propose a new type of Hopf semimetals indexed by a pair of numbers (p, q), where the Hopf number is given by pq. The Fermi surface is given by the preimage of the Hopf map, which consists of loops nontrivially linked for a nonzero Hopf number. The Fermi surface forms a torus link, whose examples are the Hopf link indexed by (1, 1), the Solomon’s knot (2, 1), the double Hopf-link (2, 2) and t...

Quantum transport of disordered Weyl semimetals at the nodal point.

Weyl semimetals are paradigmatic topological gapless phases in three dimensions. We here address the effect of disorder on charge transport in Weyl semimetals. For a single Weyl node with energy at the degeneracy point and without interactions, theory predicts the existence of a critical disorder strength beyond which the density of states takes on a nonzero value. Predictions for the conductiv...

Topological nodal line semimetals with and without spin- orbital coupling Citation

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Helicons in Weyl semimetals