Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 21: Topological Semimetals 1

TT 21.8: Vortrag

Dienstag, 17. März 2020, 11:30–11:45, HSZ 103

Non-Abelian anomalies in multi-Weyl semimetals — •Renato Miguel Alves Dantas, Francisco Peña-Benitez, Bitan Roy, and Piotr Surówka — Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Str. 38, 01187 Dresden, Germany

We construct the effective field theory for time-reversal symmetry breaking multi-Weyl semimetals (mWSMs), composed of a single pair of Weyl nodes of (anti-)monopole charge n, with n=1,2,3 in crystalline environment. From both the continuum and lattice models, we show that a mWSM with n>1 can be constructed by placing n flavors of linearly dispersing simple Weyl fermions (with n=1) in a bath of an SU(2) non-Abelian static background gauge field. Such an SU(2) field preserves certain crystalline symmetry (four-fold rotational or C4 in our construction), but breaks the Lorentz symmetry, resulting in nonlinear band spectra (namely, E ∼ (px2 + py2)n/2, but E ∼ |pz|, for example, where momenta p is measured from the Weyl nodes). Consequently, the effective field theory displays U(1) × SU(2) non-Abelian anomaly, yielding anomalous Hall effect, its non-Abelian generalization, and various chiral conductivities. The anomalous violation of conservation laws is determined by the monopole charge n and a specific algebraic property of the SU(2) Lie group, which we further substantiate by numerically computing the regular and “isospin" densities from the lattice models of mWSMs. These predictions are also supported from a strongly coupled (holographic) description of mWSMs.

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