Half-quantum mirror Hall effect.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39138173.
- Also identified by DOI 10.1038/s41467-024-51215-x and PMC identifier 11519588.
- Licence recorded as CC BY-NC-ND.
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Abstract
We predict a half-quantized mirror Hall effect induced by mirror symmetry in strong topological insulator films. These films are known to host a pair of gapless Dirac cones in the first Brillouin zone associated with surface electrons. Our findings reveal that mirror symmetry assigns a unique mirror parity to each Dirac cone, resulting in a half-quantized Hall conductance of <math xmlns="http://www.w3.org/1998/Math/MathML"><mo>±</mo> <mspace></mspace> <mfrac> <mrow> <msup><mrow><mi>e</mi></mrow> <mrow><mn>2</mn></mrow> </msup> </mrow> <mrow><mn>2</mn> <mi>h</mi></mrow> </mfrac> </math> for each cone. Despite the total electrical Hall conductance being null due to time-reversal invariance, the difference in the Hall conductance between the two cones yields a quantized Hall conductance of <math xmlns="http://www.w3.org/1998/Math/MathML"> <mfrac> <mrow> <msup><mrow><mi>e</mi></mrow> <mrow><mn>2</mn></mrow> </msup> </mrow> <mrow><mi>h</mi></mrow> </mfrac> </math> for the difference in mirror currents. The effect of helical edge mirror current - a crucial feature of this quantum effect - may, in principle, be determined by means of electrical measurements. The half-quantum mirror Hall effect reveals a type of mirror-symmetry induced quantum anomaly in a time-reversal invariant lattice system, giving rise to a topological metallic state of matter with time-reversal invariance.