2025/05/02 by Borges, Francisco, Lunts, Peter, Lee, Sung-Sik
#FOS: Physical sciences #Strongly Correlated Electrons (cond-mat.str-el)
paper · doi:10.48550/arxiv.2505.01561
We study a magnetic impurity immersed in the two-dimensional antiferromagnetic quantum critical metal (AFQCM), using the field-theoretic functional renormalization group. Critical spin fluctuations represented by a bosonic field compete with itinerant electrons to couple with the impurity through the spin-spin interaction. At long distances, the antiferromagnetic electron-impurity (Kondo) coupling dominates over the boson-impurity coupling. However, the Kondo screening is weakened by the boson with an increasing severity as the hot spots connected by the magnetic ordering wave-vector are better nested. For v0,i ≪ 1, where v0,i is the bare nesting angle at the hot spots, the temperature TKAFQCM below which Kondo coupling becomes O(1) is suppressed as \fraclog Λ/TKAFQCMlog Λ/TKFL ∼ \fracgf,iv0,i log 1/v0,i , where TKFL is the Kondo temperature of the Fermi liquid with the same electronic density of states, and gf,i is the boson-impurity coupling defined at UV cutoff energy Λ. The remarkable efficiency of the single collective field in hampering the screening of the impurity spin by the Fermi surface originates from a ultraviolet/infrared (UV/IR) mixing: bosons with momenta up to a UV cutoff actively suppress Kondo screening at low energies.