Renormalization of the elementary excitations in hole- and electron-doped cuprates due to spin fluctuations

TL;DR

This study investigates how spin fluctuations cause kink-like features in quasiparticle velocities in cuprates, revealing doping-dependent effects and connections to neutron scattering resonance peaks, with implications for understanding unconventional superconductivity.

Contribution

We demonstrate that spin fluctuations induce doping- and temperature-dependent kinks in quasiparticle velocities, differing between hole- and electron-doped cuprates, and link these to neutron resonance peaks.

Findings

Kinks appear in both normal and superconducting states in the nodal direction.

Kinks in the antinodal direction occur only below T_c.

Pronounced kinks are specific to hole-doped cuprates, not electron-doped.

Abstract

Extending our previous studies we present results for the doping-, momentum-, frequency-, and temperature- dependence of the kink-like change of the quasiparticle velocity resulting from the coupling to spin fluctuations. In the nodal direction a kink is found in both the normal and superconducting state while in the antinodal direction a kink occurs only below $T_c$ due to the opening of the superconducting gap. A pronounced kink is obtained only for hole-doped, but not for electron-doped cuprates and is characteristically different from what is expected due to electron-phonon interaction. We further demonstrate that the kink structure is intimately connected to the resonance peak seen in inelastic neutron scattering. Our results suggest similar effects in other unconventional superconductors like ${Sr}_2{RuO}_4$.