Quantum criticality out of equilibrium in the pseudogap Kondo model

Article

关键词: GAPLESS FERMI SYSTEMS;    RENORMALIZATION-GROUP;    IMPURITIES;    DOTS;   

DOI  :  10.1103/PhysRevB.85.195106

来源: SCIE

【 摘 要 】

Quantum phase transitions out of equilibrium are outstanding emergent subjects in condensed matter physics with great fundamental importance and challenges. We theoretically investigate here the nonequilibrium quantum phase transition in a generic nano-setup: the pseudogap Kondo model where a Kondo quantum dot couples to two-left (L) and right (R)-voltage-biased fermionic leads with power-law density of states (DOS) with respect to their Fermi levels mu(L/R), rho(c),(L(R))(omega) proportional to broken vertical bar omega - mu(L(R))broken vertical bar(r) with 0 < r < 1. In equilibrium (mu(L) - mu(R) = 0) and for 0 < r < 1/2, with increasing Kondo correlations this model exhibits a quantum phase transition from a unscreened local moment (LM) phase to the Kondo screened phase. At finite bias voltages and near criticality, we discover new nonequilibrium universal scaling behaviors in conductance, conduction electron T matrix, and local spin susceptibility via a controlled frequency-dependent renormalization group (RG) approach. The current-induced decoherence is key to understanding these distinct universal nonequilibrium quantum critical regimes. The relevance of our results to experiment is discussed.

【 授权许可】

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