Disordered, Low Energy Component of the Magnetic Response in Both Antiferromagnetic and Superconducting Y-Ba-Cu-O Samples
Neutron scattering lends itself as a prominently powerful and direct tool to the investigation of magnetic phenomena, under the assumption that the magnetic scattering effects can be unambiguously identified and separated from an often stronger background of non-magnetic signal. This is the case in particular with relatively small magnetic effects, such as in high Tc superconductors. Magnetic Bragg peaks and excitations around them can be well identified by their localized character in the reciprocal space. On the other hand, the hardly q dependent diffuse scattering from magnetic disorder can only be identified by the use of polarization analysis, which implies a dramatic loss of neutron intensity, i.e. sensitivity. This latter kind, much more limited studies performed by now are complementary to the single crystal work described in other contributions in this volume and they provide evidence for the existence of a disorder type, relatively low frequency range contribution to the total magnetic response in Y-Ba-Cu-O compounds. This “impurity” kind magnetism is expected to also manifest itself in µSR and NMR experiments.
KeywordsNeutron Diffraction Polarization Analysis Diffuse Scattering Magnetic Scattering Neutron Spin
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