Half-integer anomalous currents in 2D materials from a QFT viewpoint

Abstract

Charge carriers in Dirac/Weyl semi-metals exhibit a relativistic-like behavior. In this work we propose a novel type of intrinsic half-integer Quantum Hall effect in 2D materials, thereby also offering a topological protection mechanism for the current. Its existence is rooted in the 2D parity anomaly, without any need for a perpendicular magnetic field. We conjecture that it may occur in disturbed honeycomb lattices where both spin degeneracy and time reversal symmetry are broken. These configurations harbor two distinct gap-opening mechanisms that, when occurring simultaneously, drive slightly different gaps in each valley, causing a net anomalous conductivity when the chemical potential is tuned to be between the distinct gaps. Some examples of promising material setups that fulfill the prerequisites of our proposal are also listed to motivate looking for the effect at the numerical and experimental level.

12 pages, 6 figures, published version, one figure added

References in corpus (8)

• The electronic properties of graphene
• Chiral tunneling and the Klein paradox in graphene
• Valley Dependent Optoelectronics from Inversion Symmetry Breaking
• AC conductivity of graphene: from tight-binding model to 2+1-dimensional quantum electrodynamics
• Coupling the valley degree of freedom to antiferromagnetic order
• Unveiling pseudospin and angular momentum in photonic graphene
• Boundary Conformal Field Theory and a Boundary Central Charge
• Quantization of spin Hall conductivity in two-dimensional topological insulators versus symmetry and spin-orbit interaction

Cited by in corpus (6)

• Electron-Photon Vertex and Dynamical Chiral Symmetry Breaking in Reduced QED: An Advanced Study of Gauge Invariance
• Non-perturbative field theoretical aspects of graphene and related systems
• Strongly interacting matter in extreme magnetic fields
• On valley asymmetry in a topological interaction for quasi-particles
• Parity anomaly with impurities and the Pauli--Villars subtraction
• Topological insulator realization induced by fermionic interaction through BF mediators