High Energy Spin Excitations in Electron-Doped Superconducting Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-δ}$ with $T_c=21$ K

Abstract

We use high-resolution inelastic neutron scattering to study the low-temperature magnetic excitations of electron-doped superconducting Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-δ}$ ($T_c=21\pm 1$ K) over a wide energy range (4 meV$\le\hbarω\le 330$ meV). The effect of electron-doping is to cause a wave vector ($Q$) broadening in the low-energy ($\hbarω\le 80$ meV) commensurate spin fluctuations at ($π$,$π$) and to suppress the intensity of spin-wave-like excitations at high energies ($\hbarω\ge 100$ meV). This leads to a substantial redistribution in the spectrum of the local dynamical spin susceptibility $χ^{\prime\prime}(ω)$, and reveals a new energy scale similar to that of the lightly hole-doped YB$_2$Cu$_3$O$_{6.353}$ ($T_c=18$ K).