a Institut Laue-Langevin (ILL), Bo?ˆte Postale 156, F-38042 Grenoble, France b European Commission, JRC, Institute for Transuranium Elements (ITU), Postfach 2340, D-76125Karlsruhe, Germany
Abstract:
Neutron scattering results on single crystals shed light on the static and dynamic properties of the superconductor () PuCoGa5 and its isostructural but antiferromagnetic () homologue NpCoGa5. By polarized neutron diffraction the magnetization density in the paramagnetic state of both compounds has been inferred. The microscopic magnetization of NpCoGa5 is consistent with the orbital and spin components of a localized Np3+ magnetic moment. In the case of PuCoGa5 the microscopic magnetization is small, temperature-independent and cannot be described as a localized Pu3+ magnetic moment. For NpCoGa5 a dynamic magnetic signal has been observed by three-axis spectroscopy in the antiferromagnetically ordered state. The magnetic signal is strongest at the antiferromagnetic zone center and an energy transfer of about 5 meV. Magnetic fluctuations persist at this position in the paramagnetic state. The dynamic response is similar to the dynamic response observed in other actinide intermetallic compounds. This supports the possibility that magnetic fluctuations could also be present in the paramagnetic superconductor PuCoGa5.
) PuCoGa5 and its isostructural but antiferromagnetic (
) homologue NpCoGa5. By polarized neutron diffraction the magnetization density in the paramagnetic state of both compounds has been inferred. The microscopic magnetization of NpCoGa5 is consistent with the orbital and spin components of a localized Np3+ magnetic moment. In the case of PuCoGa5 the microscopic magnetization is small, temperature-independent and cannot be described as a localized Pu3+ magnetic moment. For NpCoGa5 a dynamic magnetic signal has been observed by three-axis spectroscopy in the antiferromagnetically ordered state. The magnetic signal is strongest at the antiferromagnetic zone center and an energy transfer of about 5 meV. Magnetic fluctuations persist at this position in the paramagnetic state. The dynamic response is similar to the dynamic response observed in other actinide intermetallic compounds. This supports the possibility that magnetic fluctuations could also be present in the paramagnetic superconductor PuCoGa5.