Nonequilibrium dynamics of a singlet-triplet Anderson impurity near the quantum phase transition.

摘要: We study the singlet-triplet Anderson model (STAM) in which a configuration with doublet is hybridized another containing singlet and triplet, as minimal to describe two-level quantum dots coupled two metallic leads effectively one-channel fashion. The has phase transition separates regions of ground state. limits integer valence STAM (which include similar underscreened spin-1 Kondo model) are derived used predict behavior conductance through system on both sides transition, where it jumps abruptly. At special critical line, can be mapped an infinite- U ordinary (OAM) plus free spin 1/2. use this mapping obtain spectral densities function those OAM at transition. Using non-crossing approximation (NCA), we calculate temperature bias voltage, determine changes that take place separation density into triplet part allows us shed light underlying physics explain shoulder observed recently zero transport measurements single fullerene molecule (Roch et al 2008 Nature 453 633). structure three peaks nonequilibrium these experiments also explained.