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"Probing magnon polarization using a new neutron scattering technique: the example of uranium dioxide."

Relatore: Dr. Elizabeth Blackburn

Aula Newton
29 Settembre 2004 ore 15.30

Recently, full (3-D)polarization analysis of neutron beams has become possible.This has been done for both elastic and inelastic scattering,using the CRYOPAD instrument option at the Institut Laue-Langevin, Grenoble. This technique will be explained, concentrating on the inelastic case. Possible applications will be described. One example is the magnetic excitations in uranium dioxide. This material is one of the actinide dioxides. These materials display significantly different properties, on changing the number of 5f electrons present on the actinide. The magnetic behaviour of this series will be briefly outline, concentrating on UO2, NpO2 and PuO2. Uranium dioxide is a local moment system, with well defined magnetic excitations. Using 3-D polarization analysis, the eigenvectors of individual magnons can be probed, and then compared with predictions from spin wave theory.