title: Kondo destruction and valence fluctuations in an Anderson model.
abstract: Unconventional quantum criticality in heavy-fermion systems has been extensively analyzed in terms of a critical destruction of the Kondo effect. Motivated by a recent demonstration of quantum criticality in a mixed-valent heavy-fermion system, β-YbAlB(4), we study a particle-hole-asymmetric Anderson impurity model with a pseudogapped density of states. We demonstrate Kondo destruction at a mixed-valent quantum critical point, where a collapsing Kondo energy scale is accompanied by a singular charge-fluctuation spectrum. Both spin and charge responses scale with energy over temperature (ω/T) and magnetic field over temperature (H/T). Implications for unconventional quantum criticality in mixed-valence heavy fermions are discussed.
authors.affiliation: Department of Physics & Astronomy, Rice University, Houston, Texas 77005, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Pixley
authors.forename: Stefan
authors.initials: S
authors.lastname: Kirchner
authors.forename: Kevin
authors.initials: K
authors.lastname: Ingersent
authors.forename: Qimiao
authors.initials: Q
authors.lastname: Si