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

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 ($\approx 6.8k_B{T}_c$) is observed below the superconducting transition temperature $T_c$. The resonance mode is energy-resolution limited and exhibits an intrinsic momentum width of about $0.2{\mathring{\mathrm{A}}}^{-1}$, 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.

4 pages, 4 figures