Non-equilibrium magnetization dynamics of ferromagnetically coupled Kondo spins

TL;DR

This paper provides an analytical study of the non-equilibrium decay of local magnetization in the ferromagnetic Kondo model using an extended flow-equation method, revealing persistent memory effects at zero temperature.

Contribution

It introduces an analytical approach to describe non-equilibrium dynamics in the ferromagnetic Kondo model, extending flow-equation techniques to this context.

Findings

Analytical solutions for magnetization decay at short and long times.

System retains memory of initial state at long times.

Method applicable at zero temperature.

Abstract

An analytical description of non-equilibrium phenomena in interacting quantum systems is rarely possible. Here we present one example where such a description can be achieved, namely the ferromagnetic Kondo model. In equilibrium, this model is tractable via perturbative renormalization-group techniques. We employ a recently developed extension of the flow-equation method to calculate the non-equilibrium decay of the local magnetization at zero temperature. The flow equations admit analytical solutions which become exact at short and long times, in the latter case revealing that the system always retains a memory of its initial state.