Unidirectional transport in electronic and photonic Weyl materials by Dirac mass engineering

Abstract

Unidirectional transports have been observed in two-dimensional systems, however, so far they have not been experimentally observed in three-dimensional bulk materials. In this theoretical work we show that the recently discovered Weyl materials provide a platform for unidirectional transports inside bulk materials. With high experimental feasibility, a complex Dirac mass can be generated and manipulated in the photonic Weyl crystals, creating unidirectionally propagating modes observable in transmission experiments. Possible realization in (electronic) Weyl semimetals is also studied. We show in a lattice model that, with a short-range interaction, the desired form of the Dirac mass can be spontaneously generated in a first-order transition.

Topological invariants of Floquet systems: General formulation, special properties, and Floquet topological defects

“…These chiral modes have deep fieldtheoretical origin in the continuum field theory 130,131 . It has been pointed out that the dislocations in the charge density wave in Weyl semimetals carry chiral modes [132][133][134][135][136] , which brings this conception closer to potential experimental realization. The photonic analog has also been proposed 129 .…”

“…We shall focus on the n = 1 case for simplicity. Sufficiently far away from the line defect, the Bloch Hamiltonian reads If the driving term m d cos ωt σ 0 τ x is removed from the Hamiltonian, static line defects with chiral modes 29,133 can be constructed in certain regimes of (t 1 , t 2 , m 0 ), provided that the second Chern number in the (k x , k y , k z , θ) parameter space is nonzero. In this work we are more interested in the effects of nonzero m d , which is responsible for the Floquet chiral modes.…”

Response properties of axion insulators and Weyl semimetals driven by screw dislocations and dynamical axion strings

“…31, and then discussing how this theory is coupled to geometric perturbations. The AI is generated by spontaneous chiral symmetry breaking in three dimensional Weyl semimetals [31,43]. For a (two-node) WSM, breaking the chiral symmetry is accomplished by a commensurate translation symmetry breaking that nests the Weyl nodes.…”

Tunable Weyl Points in Periodically Driven Nodal Line Semimetals

“…The nodal point semimetals include Dirac semimetals(DSM) [4][5][6][7][8][9][10][11][12][13][14] and Weyl semimetals(WSM) [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31]. The main feature of the band structures of DSMs and WSMs is the linear bandtouching points ("Dirac points" and "Weyl points"), which are responsible for most of their interesting properties, including novel phenomena induced by the chiral anomaly [32][33][34][35][36][37][38][39][40][41][42][43][44]. NLSMs [45][46][47][48][49][50][51][52]…”