Evidence for two charge sectors in the strange metal phase of overdoped cuprates

In this presentation, I describe my group’s recent exploration of the low-temperature (T < 50 K) magnetotransport in two families of single-layer cuprates - Tl2201 and La-Bi2201 - across the so-called strange metal regime. Firstly, we report a study of the Hall number n_H(0) in the low T, high field limit that within conventional transport theory, is simply related to the number of charge carriers. We find that the hole concentration inferred from n_H(0) increases smoothly from p to 1 + p, where p is the number of holes doped into the parent insulating state, over a wide range of doping beyond the critical hole doping at which the pseudogap in the single-particle response closes. We also report the observation of quadrature scaling in the magnetoresistance - believed to be associated with Planckian dissipation - as well as other signatures of incoherent transport. From analysis of the Hall and magnetoresistance, we conclude that there are in fact two charge sectors in the strange metal phase of overdoped cuprates, one containing coherent quasiparticles, the other incoherent `Planckian' dissipators.