1997/07/30 by Anirvan M. Sengupta, Sengupta, Anirvan M.
Physics and Astronomy · #FOS: Physical sciences #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #Rare-earth and actinide compounds #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.cond-mat/9707316
openalex publication_date 1997/07/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
I consider models with an impurity spin coupled to a fluctuating gaussian field with or without additional Kondo coupling of the conventional sort. In the case of isotropic fluctuations, the renormalisation group flows for these models have controlled fixed points when the autocorrelation of the gaussian field h(t), ∼ 1\over t2-ε with small positive ε. In absence of any additional Kondo coupling, I get powerlaw decay of spin correlators, ∼ 1\over tε . For negative ε, the spin autocorrelation is constant in long time limit. The results agree with calculations in Schwinger Boson mean field theory. In presence of a Kondo coupling to itinerant electrons, the model shows a phase transition from a Kondo phase to a field fluctuation dominated phase. These models are good starting points for understanding behaviour of impurities in a system near a zero-temperature magnetic transition. They are also useful for understanding the dynamical local mean field theory of Kondo lattice with Heisenberg (spin-glass type) magnetic interactions.