Neutron scattering techniques are used to study the magnetic excitations of the Er ions in superconducting ErBa2Cu3O7, a system where the Er ions order antiferromagnetically at TN=0.62 K and the sublattice magnetization obeys the relation for a 2D S=1/2 Ising model. Our data, which were taken on a cold neutron triple axis spectrometer using a horizontally focusing analyzer, reveal that there is a large gap of about 0.20 meV in the excitation spectrum, about four times the thermal energy kTN, as expected for an Ising system. However, we also observe dispersion of the spin waves in the a-b plane. These excitations are found to renormalize with temperature and only diffuse paramagnetic scattering is observed well above the ordering temperature.
S. Skanthakumar et al., "Spin Dynamics of Er³⁺ in ErBa₂Cu₃O7-δ," Journal of Applied Physics, vol. 81, no. 8 PART 2B, pp. 4934 - 4936, American Institute of Physics (AIP), Apr 1997.
The definitive version is available at https://doi.org/10.1063/1.365002
Materials Science and Engineering
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© 1997 American Institute of Physics (AIP), All rights reserved.
01 Apr 1997