Incoherent transport across the strange metal regime of highly overdoped cuprates

TL;DR

This paper investigates the unconventional transport properties of overdoped cuprates in the strange metal regime, revealing evidence for two distinct charge sectors despite a single-band structure, challenging existing theories.

Contribution

It provides experimental evidence for dual charge sectors in cuprate strange metals beyond the quantum critical point, with implications for understanding their anomalous transport behavior.

Findings

Magnetoresistance exhibits quadrature scaling and becomes linear at high H/T ratios.

Magnitude of magnetoresistance exceeds predictions of conventional theory.

Transport properties suggest coexistence of coherent quasiparticles and scale-invariant dissipators.

Abstract

Strange metals possess highly unconventional transport characteristics, such as a linear-in-temperature ($T$) resistivity, an inverse Hall angle that varies as $T^2$ and a linear-in-field ($H$) magnetoresistance. Identifying the origin of these collective anomalies has proved profoundly challenging, even in materials such as the hole-doped cuprates that possess a simple band structure. The prevailing dogma is that strange metallicity in the cuprates is tied to a quantum critical point at a doping $p*$ inside the superconducting dome. Here, we study the high-field in-plane magnetoresistance of two superconducting cuprate families at doping levels beyond $p*$. At all dopings, the magnetoresistance exhibits quadrature scaling and becomes linear at high $H/T$ ratios. Moreover, its magnitude is found to be much larger than predicted by conventional theory and insensitive to both impurity scattering and magnetic field orientation. These observations, coupled with analysis of the zero-field and Hall resistivities, suggest that despite having a single band, the cuprate strange metal phase hosts two charge sectors, one containing coherent quasiparticles, the other scale-invariant `Planckian' dissipators.