Quantum dot in the pseudogap Kondo state

TL;DR

This paper explores the unique transport phenomena of a quantum dot coupled to leads with a power-law density of states, revealing non-traditional Kondo effects and quantum criticality.

Contribution

It provides a theoretical analysis of the transport properties in a quantum dot system with a pseudogap Kondo state, highlighting novel physical behaviors.

Findings

Non-saturating Coulomb blockade peak widths

Non-unitary Kondo peak between Coulomb peaks

Absence of conductance away from particle-hole symmetry at low temperatures

Abstract

We investigate the transport properties of a (small) quantum dot connected to Fermi liquid leads with a power-law density of states (DOS). Such a system, if experimentally realizable, will have interesting physical properties including: (i) non-saturating Coulomb blockade peak widths; (ii) a non-unitary Kondo peak symmetrically placed between the Coulomb blockade peaks; (iii) an absence of conductance away from particle-hole symmetry at sufficiently low temperatures; and (iv) evidence of a quantum critical point as a function of dot-lead hopping. These properties are compared and contrasted with one dimensional Luttinger systems exhibiting a power-law "tunneling-DOS".