Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 52: Quantum Impurities and Kondo Physics
TT 52.11: Vortrag
Donnerstag, 4. April 2019, 12:15–12:30, H7
Residual Conduction in Kondo Insulators — •Emanuele Maggio, Matthias Pickem, and Jan Tomczak — Institute of Solid State Physics, TU Wien, A-1040 Vienna, Austria
Correlated narrow-gap semiconductors [1] display a pronounced tendency towards resistivity saturation at low temperatures. Especially in heavy-fermion Kondo insulators, the persistence of residual conduction is a long-standing puzzle. Theories of conventional semi-conductors hint at extrinsic impurity-states. Complementarily, it has recently been suggested that certain Kondo insulators may harbour surface states that are protected by topological properties of their bulk electronic structure [2]. Experimentally, there is contrasting evidence (e.g., [3]), insinuating that the nature of conducting states in Kondo insulators may be non-universal. In this contribution, we put forward a new interpretation: we attribute the deviation from activated behaviour in the resistivity to short-comings of the relaxation-time approximation in the calculation of transport properties for correlated materials. Based on a dynamical mean-field theory description and a new linear-response transport scheme, we investigate Ce-based Kondo insulators*such as the prototypical Ce3Bi4Pt3. Finding overall good agreement with experiment, we characterise the resistivity in terms of a crossover temperature T* marking the onset of saturation. Studying its control parameters, we delineate the applicability of our scenario to other systems.
J. M. Tomczak, J. Phys.: Condens Mat 30, 183001 (2018)
M. Dzero et al., Phys. Rev. Lett. 104, 106408 (2010)
N. Wakeham et al., Phys. Rev. B 94, 035127 (2016)