Interaction-enhanced magnetically ordered insulating state at the edge of a two-dimensional topological insulator

Abstract

We develop a theory of the correlated magnetically ordered insulating state at the edge of a two-dimensional topological insulator. We demonstrate that the gapped spin-polarized state, induced by the application of the magnetic field $B$, is naturally facilitated by electron interactions, which drive the critical easy-plane ferromagnetic correlations in the helical liquid. As the key manifestation, the gap $\De$ in the spectrum of collective excitations, which carry both spin and charge, is enhanced and exhibits a scaling dependence $\De \propto B^{1/(2-K)}$, controlled by the Luttinger liquid parameter $K$. This scaling dependence could be probed through the activation behavior $G \sim (e^2/h) \exp(- \De/T)$ of the longitudinal conductance of a Hall-bar device at lower temperatures, providing a straightforward way to extract the parameter $K$ experimentally. Our findings thus suggest that the signatures of the interaction-driven quantum criticality of the helical liquid could be revealed already in a standard Hall-bar measurement.

5 pages, 3 figs; v2: published version

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Cited by in corpus (12)

• Observation of second-order topological insulators in sonic crystals
• Large magnetic gap at the Dirac point in a Mn-induced Bi${}_2$Te${}_3$ heterostructure
• Correlation effects in two-dimensional topological insulators
• Hyperfine interactions in two-dimensional HgTe topological insulators
• Coulomb blockade microscopy of spin density oscillations and fractional charge in quantum spin Hall dots
• Spin textures of strongly correlated spin Hall quantum dots
• Unusual spin dynamics in topological insulators
• Spin-polarized tunneling into helical edge states: asymmetry and conductances
• Magnetoelectric-field electrodynamics: Search for magnetoelectric point scatterers
• Nonequilibrium Spectroscopy of Topological Edge Liquids
• Manipulation of photonic topological edge and corner states via trivial claddings
• Engineering Majorana Kramers Pairs In Synthetic High Spin Chern Insulators