Year: 2014
Type: article
Abstract: We calculate the dynamical structure factor $S(q,\ensuremath{\omega})$ of a weakly interacting helical edge state in the presence of a magnetic field $B$. The latter opens a gap of width $2B$ in the single-particle spectrum, which becomes strongly nonlinear near the Dirac point. For chemical potentials $|\ensuremath{\mu}|>B$, the system then behaves as a nonlinear helical Luttinger liquid, and a mobile-impurity analysis reveals power-law singularities in $S(q,\ensuremath{\omega})$ which depend on the interaction strength as well as on the spin texture of the edge states. For $|\ensuremath{\mu}|<B$, the low-energy excitations are gapped, and we determine $S(q,\ensuremath{\omega})$ by using an analogy to exciton physics.
Source: Physical Review B
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2078181981