Evolution of the strange-metal scattering in momentum space of electron-doped ${\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_4$

TL;DR

This study investigates how the scattering properties in momentum space of electron-doped cuprates evolve with doping and temperature, revealing a transition from linear to quadratic energy dependence and a dichotomy in scattering rates.

Contribution

It provides the first systematic doping, momentum, and temperature-dependent ARPES measurements of Im Σ(k, ω) in electron-doped cuprates, highlighting the evolution of strange metal scattering.

Findings

Im Σ ∝ ω at low doping and temperature

Im Σ ∝ ω^2 at high doping and temperature

Dichotomy in scattering rates along nodal and antinodal directions

Abstract

The linear-in-temperature resistivity is one of the important mysteries in the strange metal state of high-temperature cuprate superconductors. To uncover this anomalous property, the energy-momentum-dependent imaginary part of the self-energy Im ${\rm \Sigma}(k, \omega)$ holds the key information. Here we perform systematic doping, momentum, and temperature-dependent angle-resolved photoemission spectroscopy measurements of electron-doped cuprate ${\rm La}_{2-x}{\rm Ce}_x{\rm CuO}_4$ and extract the evolution of the strange metal scattering in momentum space. At low doping levels and low temperatures, Im ${\rm\Sigma} \propto \omega$ dependence dominates the whole momentum space. For high doping levels and high temperatures, Im ${\rm\Sigma} \propto \omega^2$ shows up, starting from the antinodal region. By comparing with the hole-doped cuprates ${\rm La}_{2-x}{\rm Sr}_x{\rm CuO}_4$ and ${\rm Bi}_2{\rm Sr}_2{\rm CaCu}_2{\rm O}_8$, we find a dichotomy of the scattering rate exists along the nodal and antinodal direction, which is ubiquitous in the cuprate family. Our work provides new insight into the strange metal state in cuprates.