David Le Boeuf : Loss of strange metal behaviour and carrier density at spin freezing transition in a cuprate superconductor

Strange metals – which exhibit unusual properties such as a resistivity that scales linearly with temperature – challenge our understanding of charge transport in metals. We investigate how the strange metal phase of the cuprate superconductor La2-xSrxCuO4 is impacted by field-induced antiferromagnetism. We find T-linear resistivity regime at low temperatures over an extended range of magnetic fields where magnetic moments fluctuate, and T-linear resistivity is lost when magnetic fluctuations are quenched with magnetic fields. This suggests that strange metalicity is linked to the existence of magnetic fluctuations persisting at low T and high fields. The high field emergence of static magnetism produces large insulating-like resistivity upturns inside the pseudogap phase. Our Hall effect data show that this increase in resistivity is caused by a loss of carrier density, suggesting a coupling between charge and spins that leads to the concomitent freezing of charge and spin degrees of freedom.