SU(4) Kondo effect in double quantum dots with ferromagnetic leads

Ireneusz Weymann, Razvan Chirla, Piotr Trocha, and Cătălin Paşcu Moca
Phys. Rev. B 97, 085404 – Published 5 February 2018

Abstract

We investigate the spin-resolved transport properties, such as the linear conductance and the tunnel magnetoresistance, of a double quantum dot device attached to ferromagnetic leads and look for signatures of the SU(4) symmetry in the Kondo regime. We show that the transport behavior greatly depends on the magnetic configuration of the device, and the spin-SU(2) as well as the orbital and spin-SU(4) Kondo effects become generally suppressed when the magnetic configuration of the leads varies from the antiparallel to the parallel one. Furthermore, a finite spin polarization of the leads lifts the spin degeneracy and drives the system from the SU(4) to an orbital-SU(2) Kondo state. We analyze in detail the crossover and show that the Kondo temperature between the two fixed points has a nonmonotonic dependence on the degree of spin polarization of the leads. In terms of methods used, we characterize transport by using a combination of analytical and numerical renormalization group approaches.

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  • Received 27 September 2017
  • Revised 22 November 2017

DOI:https://doi.org/10.1103/PhysRevB.97.085404

©2018 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Ireneusz Weymann1,*, Razvan Chirla2,3, Piotr Trocha1, and Cătălin Paşcu Moca2,4

  • 1Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań, Poland
  • 2Department of Physics, University of Oradea, 410087, Oradea, Romania
  • 3Faculty of Medicine and Pharmacy, Department of Preclinical Sciences, University of Oradea, 410087, Oradea, Romania
  • 4BME-MTA Exotic Quantum Phases Research Group, Budapest University of Technology and Economics, 1521 Budapest, Hungary

  • *weymann@amu.edu.pl

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Issue

Vol. 97, Iss. 8 — 15 February 2018

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