Spin Dynamics in Cuprates: Optical Conductivity of HgBa2CuO4

TL;DR

This study analyzes the electron-boson spectral density in high-temperature cuprate superconductor HgBa2CuO4 using optical data and maximum entropy, revealing a peak related to the superconducting transition temperature and its correlation with magnetic resonance.

Contribution

It introduces a new analysis of optical scattering data to extract the electron-boson spectral density in HgBa2CuO4, linking spectral features to Tc and magnetic resonance phenomena.

Findings

Spectral peaks at Omega_r are proportional to Tc.

Omega_r approximately equals 6.3 kB.Tc, matching neutron resonance.

Peak amplitudes decrease with increasing temperature.

Abstract

The electron-boson spectral density function I^2ChiOmega responsible for carrier scattering of the high temperature superconductor HgBa2CuO4 (Tc = 90 K) is calculated from new data on the optical scattering rate. A maximum entropy technique is used. Published data on HgBa2Ca2Cu3O8 (Tc = 130 K) are also inverted and these new results are put in the context of other known cases. All spectra (with two notable exceptions) show a peak at an energy (Omega_r) proportional to the superconducting transition temperature Omega_r ~= 6.3 kB.Tc. This charge channel relationship follows closely the magnetic resonance seen by polarized neutron scattering, Omega_r^{neutron} ~= 5.4 kB.Tc. The amplitudes of both peaks decrease strongly with increasing temperature. In some cases, the peak at Omega_r is weak and the spectrum can have additional maxima and a background extending up to several hundred meV.