Altermagnetism-Induced Parity Anomaly in Weak Topological Insulators

Abstract

We demonstrate that introducing altermagnetism on the surface of a weak topological insulator (TI) results in the emergence of a single massless Dirac fermion, exhibiting a parity anomaly. To explore the transport properties induced by this parity anomaly, we propose an effective two-dimensional (2D) lattice model to describe the weak TI surface. This model captures both the energy spectrum and spin texture of the weak TI surface while reducing computational complexity. We show that the weak TI surface hosts a half-integer chiral edge current under the influence of altermagnetism. Additionally, in the presence of decoherence, the Hall conductance attains a half-quantized value. Layer-resolved calculations from a 3D slab model further confirm that surface altermagnetism drives the surface Hall conductance to transition to $e^2/2h$, aligning with calculation from the 2D effective lattice model. Our findings establish a link between altermagnetism and quantum anomalies, positioning weak TIs as a potential platform for investigating the parity anomaly without a net magnetic moment.

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Cited by in corpus (5)

• Tunneling Magnetoresistance Effect in Altermagnets
• Interplay of Altermagnetic Order and Wilson Mass in the Dirac Equation: Helical Edge States without Time-Reversal Symmetry
• Quantum Anomalous Hall Effect in Ferromagnetic Metals
• The emergence of net chirality in two-dimensional Dirac fermions system with altermagnetic mass
• Helical Fermi Arc in Altermagnetic Weyl Semimetal