Title: Peter Zalom: Magnetic impurities interacting with gapped fermionic reservoirs
Number: 41/21
Status: Closing date exceeded
Begin: Wednesday, 16.06. 2021, 14:30
Tutor: Karel Carva
Location: ZOOM Meeting ID: 99673611179

Wednesday 16 June 2021 at 14:30 in Online webinar

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Mgr. Peter Zalom, Ph.D.

Institute of Physics, CAS Praha

Magnetic impurities interacting with gapped fermionic reservoirs

In our recent works, Refs. [1,2] we have derived and applied a general scheme for mapping a setup consisting of a half-filled single level quantum dot (QD) coupled to one normal metallic and two superconducting phase-biased leads onto an ordinary half-filled single impurity Anderson model with single modified tunneling density of states (TDOS). The theory allows for the otherwise unfeasible application of the standard numerical renormalization group (NRG) and enables to obtain phase-dependent local spectral properties as well as phase-dependent induced pairing and Josephson current which point towards the underlying 0-pi quantum phase transition that occurs when the metallic lead is completely detached.
Building up on the consequences of the general mapping scheme we show that semiconductor or narrow gap insulator leads have the potential to recreate the essential features of the same QPTs which follows from the presented NRG solutions to selected systems composed of half-filled QD and metal-semiconductor (narrow gap insulator) lead(s). We then concentrate on introducing a new discretization scheme to replace the standard logarithmic discretization used presently in NRG, which is however unsuitable for systems with scalar gapped TDOS

[1] P. Zalom, V. Pokorný, and T. Novotný, Physical Review B 103, 035419 (2021)
[2] P. Zalom, and T. Novotný, arXiv:2105.09555 (2021)