Magnetic resonance in the model high-temperature superconductor HgBa$_2$CuO$_{4+\delta}$

TL;DR

This study uses inelastic neutron scattering to observe a magnetic resonance in the high-temperature superconductor HgBa$_2$CuO$_{4+\delta}$, revealing insights into its magnetic excitations near optimal doping.

Contribution

It reports the detection of a well-defined antiferromagnetic resonance in HgBa$_2$CuO$_{4+\delta}$, highlighting its energy and momentum characteristics and discussing its implications for cuprate superconductivity.

Findings

Resonance energy is 56 meV, about 6.8 times k_B T_c.

Resonance mode is energy-resolution limited with a momentum width of 0.2 Å$^{-1}$.

Large mode energy suggests non-universal relation between $\\omega_r$ and T_c.

Abstract

We present an inelastic neutron scattering study of the structurally simple single-layer compound HgBa$_2$CuO$_{4+\delta}$ close to optimal doping ($T_c \approx 96$ K). A well-defined antiferromagnetic resonance with energy $\omega_r = 56$ meV ($\approx 6.8 k_BT_c$) is observed below the superconducting transition temperature $T_c$. The resonance mode is energy-resolution limited and exhibits an intrinsic momentum width of about $0.2 \mathrm{\mathring{A}^{-1}}$, consistent with prior work on several other cuprates. However, the unusually large value of the mode energy implies a non-universal relationship between $\omega_r$ and $T_c$ across different families of cuprates.