Quantum criticality in the two-channel pseudogap Anderson model: A test of the non-crossing approximation

Abstract

We investigate the dynamical properties of the two-channel Anderson model using the noncrossing approximation (NCA) supplemented by numerical renormalization-group calculations. We provide evidence supporting the conventional wisdom that the NCA gives reliable results for the standard two-channel Anderson model of a magnetic impurity in a metal. We extend the analysis to the pseudogap two-channel model describing a semi-metallic host with a density of states that vanishes in power-law fashion at the Fermi energy. This model exhibits continuous quantum phase transitions between weak- and strong-coupling phases. The NCA is shown to reproduce the correct qualitative features of the pseudogap model, including the phase diagram, and to yield critical exponents in excellent agreement with the NRG and exact results. The forms of the dynamical magnetic susceptibility and impurity Green's function at the fixed points are suggestive of frequency-over-temperature scaling.

6 pages, 10 figures, to appear in the special issue of pss on Quantum Criticality and Novel Phases (QCNP12)

References in corpus (6)

• Quantum Criticality in Heavy Fermion Metals
• Fermi-surface collapse and dynamical scaling near a quantum critical point
• Tuning Kondo physics in Graphene with gate voltage
• Quantum critical properties of the Bose-Fermi Kondo Model in a large-N limit
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Cited by in corpus (4)

• Oxygen vacancy-driven orbital multichannel Kondo effect in Dirac nodal line metals IrO2 and RuO2
• Entanglement Entropy Near Kondo-Destruction Quantum Critical Points
• Kondo-assisted switching between three conduction states in capacitively coupled quantum dots
• Quantum criticality in the spin-isotropic pseudogap Bose-Fermi Kondo model: entropy, scaling, and the g-theorem