Regensburg 2016 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 8: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 8.2: Vortrag
Montag, 7. März 2016, 10:30–10:45, H21
Effect of a magnetic moment on quantum spin Hall edge transport — •Florian Geißler1, Jukka Väyrynen2, and Leonid Glazman2 — 1Universität Würzburg, Würzburg, Germany — 2Yale University, New Haven, USA
A local magnetic moment coupled to one dimensional helical transport channels, such as the edge states of a 2D quantum spin Hall insulator, can be a source of time-reversal invariant backscattering. We study the resulting correction to the conductance as a function of temperature T, dc bias voltage V and the repulsive electron-electron interactions characterized by the Luttinger liquid parameter K<1. Such corrections display a characteristic power law dependence on V or T, with distinct scaling in the two regimes above and below the Kondo temperature, corresponding to the mechanisms of elastic and inelastic single-particle backscattering, respectively.
At energies above the Kondo temperature, the coupling to the magnetic moment can be considered weak. In this regime, if interactions are very small, K≈ 1, the correction to the conductance remains almost insensitive to V/T, even at high values of V/T. If electron interactions are more effective, 3/4<K<1, this leads to corrections with small power law exponents below 1/2. Our findings agree with the experimental observation of a weak temperature dependence of the conductance in presumably weakly interacting QSH systems like HgTe and may further provide an alternative explanation for the recent experiment in more strongly correlated InAs/GaSb samples [1].
[1] Li et al., PRL 115, 136804 (2015)).