Signature of Parity Anomaly: Crossover from One Half to Integer Quantized Hall Conductance in a Finite Magnetic Field

TL;DR

This paper investigates the parity anomaly in a semimagnetic topological insulator thin film under magnetic fields, revealing a crossover in Hall conductance that confirms the anomaly and links band topology with quantum field theory.

Contribution

It demonstrates the crossover from half-quantized to integer quantized Hall conductance in a finite magnetic field, providing experimental evidence of the parity anomaly in condensed matter.

Findings

Observation of half-quantized Hall conductance due to parity anomaly

Crossover from metallic to insulating phase with changing magnetic field

Hall conductance serves as an indicator for parity anomaly

Abstract

The pursuit of understanding parity anomaly in condensed matter systems has led to significant advancements in both theoretical and experimental research in recent years. In this study, we explore the parity anomaly of massless Dirac fermions in a semimagnetic topological insulator (TI) thin film subjected to a finite magnetic field. Our findings reveal an anomalous half-quantized Hall conductance arising from the occupied electronic states far below the Fermi level, which is directly associated with the parity anomaly. This observation demonstrates a crossover from one-half quantized Hall conductance in a metallic phase at zero field to one or zero quantized Hall conductance in the insulating phase at a strong field in the presence of disorders, serving as a key indicator for confirming parity anomaly. Our work provides valuable insights into the intricate relationship between band topology in condensed matter systems and quantum anomaly in quantum field theory.