大型放射光施設 SPring-8

日   時 ： 2005年10月4日 13:30-15:00

講演者 ： Dr. Stuart Wilkins
所   属 ： ESRF

講演要旨
　　Orbital ordering occurs when long-range order of anisotropic charge distributions develops in a material. Noted systems where this has been studied are the manganites [1], where long range ordering of the 3d electrons have been discovered and UPd3 [2] where the 5f electrons are shown to long-range order. Neutron diffraction is not sensitive to such effects, but resonance x-ray scattering (RXS) at an elemental absorption edge, combined with an analysis of the outgoing polarization as a function of the azimuthal angle, is particularly powerful. We report here experiments on both the magnanites La0.5Sr1.5MnO4 [1] and LaSr2Mn2O7 [3] and the actinide oxides UO2 [4] and NpO2 [5], as well as a mixed (U,Np)O2 system [6].

References
[1] S. B. Wilkins et al., PRL 91 (2003) 167205
[2] D. McMorrow et al., PRL 87 (2001) 057201
[3] S. B. Wilkins et al., submitted to Physical Review Letters
[4] S. B. Wilkins et al., submitted to Physical Review Letters
[5] J. A. Paixao et al, PRL 89 (2002) 187202
[6] S. B. Wilkins et al. PR B 70 (2004) 214402