LOW-ENERGY MAGNETIC EXCITATIONS IN ND2-XCEXO4

The low-energy part (($) over bar h omega less than or equal to 2 meV) of the magnetic excitations of polycrystalline samples of Nd2-xCexCuO4 with x = 0, 0.16 and 0.20 has been measured with inelastic magnetic neutron scattering between 1.8 and 300 K. All observed magnetic scattering originates from transitions within the ground-state doublet of Nd3+. For Nd2CuO4 the response is inelastic at T = 1.8 K with Q-dependent positions and intensities of two strong and one weak mode. For x = 0.16 and 0.20 the magnetic response is mainly quasi-elastic with some residual inelastic intensity at low-Q values. For the higher temperatures all spectra become quasi-elastic. The shape of the response changes between 40 and 190 K from Gaussian to Lorentzian.