Axion response in gapless systems

Abstract

The strong topological insulator in 3D is expected to realize a quantized magneto-electric response, the so-called axion response. However, many of the materials predicted to be topological insulators have turned out to be metallic, with bulk Fermi surfaces. Following the result of Bergman et al. (Phys. Rev. B 82, 195417 (2010)) that the helical surface states of the topological insulator persist even when the band structure gap is closed, we explore the fate of the magneto-electric response in such systems. We find a non-quantized magneto-electric coupling remains once a bulk Fermi surface opens - a non-universal axion response. More generally we find that higher dimensional analogs of the intrinsic anomalous Hall effect appear for \emph{every} Chern form - non-quantized response coefficients for gapless systems, as opposed to quantized transport coefficients in gapped systems, both with a topological origin. In particular, the non-quantized magneto-electric response in 3D descends from the intrinsic anomalous Hall effect analog in 4D.

References in corpus (8)

• The electronic properties of graphene
• Topological Insulators
• Topological Field Theory of Time-Reversal Invariant Insulators
• First direct observation of Spin-textures in Topological Insulators : Spin-resolved ARPES as a probe of topological quantum spin Hall effect and Berry's phase
• Bulk Fermi surface coexistence with Dirac surface state in Bi${}_2$Se${}_3$: a comparison of photoemission and Shubnikov-de Haas measurements
• The development of ferromagnetism in the doped topological insulator Bi2-xMnxTe3
• Angular-dependent oscillations of the magnetoresistance in Bi_2Se_3 due to the three-dimensional bulk Fermi surface
• Bulk metals with helical surface states

Cited by in corpus (14)

• Axionic field theory of (3+1)-dimensional Weyl semi-metals
• Local invariants identify topology in metals and gapless systems
• Disorder-induced metal-insulator transitions in three-dimensional topological insulators and superconductors
• Adiabatically Induced Orbital Magnetization
• Topological response theory of doped topological insulators
• Topological metal behavior in GeBi2Te4 single crystals
• Finite frequency magnetoelectric response of three dimensional Topological Insulators
• Effects of surface-bulk hybridization in 3D topological `metals'
• Disordered topological metals
• Transport through a disordered topological-metal strip
• Absence of helical surface states in bulk semimetals with broken inversion symmetry
• Green's Function Method for Line Defects and Gapless Modes in Topological Insulators : Beyond Semiclassical Approach
• Unconventional topological phase transition from semimetal to insulator in SnBi2Te4: Role of anomalous thermal expansion
• A thermodynamic measure of the Magneto-electric coupling in the 3D topological insulator