Anomalous relaxation and strange-metal behaviour

S.Caprara (Sapienza Università Rome)

A strange-metal behavior is observed in many distinct physical systems. I shall discuss a proposal that relates this behavior to the presence of slow collective excitations that have an anomalous relaxational dynamics and are coupled to conduction electrons. The main consequence of the slow dynamics of the collective excitations is to endow the conduction electrons with a linear-in-temperature scattering rate, responsible for the linear-in-temperature resistivity that is the hallmark of a strange-metal behavior. These slow collective excitation also contribute to the anomalous thermodynamic and thermal transport properties of theses systems. Excitations of this kind have indeed been detected by means of resonant inelastic X-ray scattering in cuprates, that are one of the very many systems exhibiting a strange-metal behavior.