Magnetic-field-induced mixed-level Kondo effect in two-level systems

Journal Article · Mon Oct 17 04:00:00 EDT 2016 · Physical Review B

DOI:https://doi.org/10.1103/PhysRevB.94.155130· OSTI ID:1334526

Wong, Arturo; Ngo, Anh T.; Ulloa, Sergio E.

We consider a two-orbital impurity system with intra-and interlevel Coulomb repulsion that is coupled to a single conduction channel. This situation can generically occur in multilevel quantum dots or in systems of coupled quantum dots. For finite energy spacing between spin-degenerate orbitals, an in-plane magnetic field drives the system from a local-singlet ground state to a "mixed-level" Kondo regime, where the Zeeman-split levels are degenerate for opposite-spin states. We use the numerical renormalization group approach to fully characterize this mixed-level Kondo state and discuss its properties in terms of the applied Zeeman field, temperature, and system parameters. Under suitable conditions, the total spectral function is shown to develop a Fermi-level resonance, so that the linear conductance of the system peaks at a finite Zeeman field while it decreases as a function of temperature. These features, as well as the local moment and entropy contribution of the impurity system, are commensurate with Kondo physics, which can be studied in suitably tuned quantum dot systems.

• Research Organization: Argonne National Lab. (ANL), Argonne, IL (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences and Engineering Division
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1334526
• Journal Information: Physical Review B, Journal Name: Physical Review B Journal Issue: 15 Vol. 94; ISSN 2469-9950; ISSN PRBMDO
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

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