High Energy Spin Dynamics in the electron-doped high-T$_{c}$ cuprate Pr$_{.88}$LaCe$_{.12}$CuO$_{4}$ (T$_{c}$=21K)

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$_{4-\delta }$ (T$_{c}$=21 K) over a wide energy range (4 meV$<$hbar $\omega <$ 260 meV). The effect of electron-doping and superconductivity is to cause a wave vector broadening in the low-energy ($<$50 meV) commensurate spin fluctuations at ($\pi $, $\pi )$ and to suppress the intensity of spin-wave-like excitations at high energies ($>$ 80 meV). This leads to a substantial redistribution in the spectrum of the local dynamical spin susceptibility $\chi $''($\omega )$, and reveals a new energy scale considerably smaller than that of the hole-doped materials [1]. [1] Stephen D. Wilson et. al., PRL submitted (2005).