Regensburg 2013 – scientific programme
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MA: Fachverband Magnetismus
MA 46: Topological Insulators 5 (jointly with DS, HL, MA, and O)
MA 46.1: Talk
Friday, March 15, 2013, 09:30–09:45, H18
Structure factor of a weakly interacting helical liquid — •Suhas Gangadharaiah1,2, Thomas L. Schmidt2, and Daniel Loss2 — 1Indian Institute of Science Education and Research, Bhopal, India — 2Department of Physics, University of Basel, CH-4056 Basel, Switzerland
We calculate the density structure factor S(q,ω) of a weakly interacting helical liquid in the presence of a magnetic field B. The latter opens a gap of width 2B in the single-particle spectrum є±(k), and leads to a strongly nonlinear spectrum near k = 0. For chemical potentials µ > B, the system then behaves as a nonlinear helical Luttinger liquid, and a mobile-impurity analysis reveals interaction-dependent power-law singularities in S(q,ω). For µ < B, the low-energy excitations are gapped, and we determine S(q,ω) by using an analogy to exciton physics. We discuss the implications of the magnetic field induced non-linear spectrum on the Coulomb drag between the helical liquids.