Absolute measurements of the high-frequency magnetic dynamics in high-Tc superconductors

TL;DR

This paper reviews high-frequency magnetic susceptibility measurements in high-Tc superconductors, revealing how doping affects spectral weight and spin wave intensity, with results placed on an absolute scale for systematic comparison.

Contribution

It provides absolute intensity measurements of magnetic dynamics in high-Tc superconductors, enabling direct comparison with theoretical models and revealing doping-induced spectral redistributions.

Findings

Dramatic renormalization of spin wave intensity in parent compounds

Doping causes broadening in wave vector and spectral weight redistribution

Measurements are placed on an absolute intensity scale for systematic analysis

Abstract

We review recent measurements of the high-frequency dynamic magnetic susceptibility in the high-$T_c$ superconducting systems La$_{2-x}$Sr$_{x}$CuO$_4$ and YBa$_2$Cu$_3$O$_{6+x}$. Experiments were performed using the chopper spectrometers HET and MARI at the ISIS spallation source. We have placed our measurements on an absolute intensity scale, this allows systematic trends to be seen and comparisons with theory to be made. We find that the insulating S=1/2 antiferromagnetic parent compounds show a dramatic renormalization of the spin wave intensity. The effect of doping on the response is to cause broadenings in wave vector and large redistributions of spectral weight in the frequency spectrum.