Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 6: Kondo Physics, f-Electron Systems and Heavy Fermions
TT 6.2: Vortrag
Montag, 5. September 2022, 15:15–15:30, H22
Two-channel Kondo effect in locally non-centrosymmetric systems — •Daniel Hafner — Max Planck Institute for Chemical Physics of Solids, Dresden, Germany
A scalable model is presented, which shows that two-channel Kondo (2CK) physics is possible in centrosymmetric crystals, in which the spin-orbit (SO) energy splitting α of conduction electron states is stronger than the hopping parameter t between an inversion symmetric pair of them. The potential difference introduced by the SO coupling effectively suppresses the hopping and disentangles the conduction states into two channels, allowing them to independently couple to impurity spins. If the impurity sites are located on inversion centers, the identical Kondo coupling strengths lead to a symmetrical 2CK effect below the Kondo temperature T2CK. Since the coupling between sectors is still present, the impurity spin is eventually fully quenched by the entangled part of the conduction electrons in a single-channel Kondo effect below T1CK. For α/t>√2, a temperature region T2CK>T>T1CK with dominant 2CK physics is found. If the impurities are not located on inversion centers, the resulting channel-asymmetric 2CK model introduces a third temperature scale. Below this, each of two inversion-symmetric impurity sites is screened by one of the two channels, creating a Fermi liquid made up of two types of Kondo singlets linked by inversion symmetry. The similarity of the presented 2CK model to the well established 2CK effect in quantum dots is discussed as well as possible candidate materials like the locally non-centrosymmetric heavy-fermion superconductor CeRh2As2.