Anomalous thermopower from the drag of overdamped collective modes

Abstract

Inspired by the observation of a Seebeck coefficient ratio that exhibits a seemingly logarithmic divergence at low temperature in high-temperature superconducting cuprates, we show that a mechanisms similar to the standard phonon drag can give rise to anomalies in the thermopower of a metal, if the dragged collective mode is overdamped, with a damping coefficient that increases with lowering the temperature. Our finding adds a piece to the puzzle of the strange-metal behavior observed in many different systems and supports our proposal that overdamped charge density fluctuations can be responsible of such a behavior in high-temperature superconducting cuprates.