Interpretation of difference between bulk magnetic susceptibility and “local magnetic susceptibility” detected by core excitation magnetic circular dichroism

Abstract

The “local magnetic susceptibility” of some coherent Kondo materials was measured with core excitation magnetic circular dichroism (MCD) and was compared to the bulk magnetic susceptibility measurements. Remarkable difference between the local and bulk susceptibility was interpreted in terms of the local recovery of coherence just after the core excitation together with asymmetry of excitation and relaxation. This mechanism is analyzed in terms of time-evolution of a model with two subsystems, one of which is directly coupled to the heat reservoir while the other is not. This asymmetry and the local recovery of coherence reduces the effective hybridization, making the “coherent Kondo” into a single-site event and largely lower the Kondo temperature.