X-ray and neutron scattering

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The first paper by WL Bragg - what and when?

CRYSTALLOGRAPHY REVIEWS 19:3 (2013) 117-124
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Ground state in a half-doped manganite distinguished by neutron spectroscopy

Physical Review Letters 109:23 (2012)

Authors:

GE Johnstone, TG Perring, O Sikora, D Prabhakaran, AT Boothroyd

Abstract:

We have measured the spin-wave spectrum of the half-doped bilayer manganite Pr(Ca,Sr)2Mn2O7 in its spin, charge, and orbital ordered phase. The measurements, which extend throughout the Brillouin zone and cover the entire one-magnon spectrum, are compared critically with spin-wave calculations for different models of the electronic ground state. The data are described very well by the Goodenough model, which has weakly interacting ferromagnetic zig-zag chains in the CE-type arrangement. A model that allows ferromagnetic dimers to form within the zigzags is inconsistent with the data. The analysis conclusively rules out the strongly bound dimer (Zener polaron) model. © 2012 American Physical Society.
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Ground state in a half-doped manganite distinguished by neutron spectroscopy

(2012)

Authors:

GE Johnstone, TG Perring, O Sikora, D Prabhakaran, AT Boothroyd
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Strongly momentum-dependent screening dynamics in La$_{0.5}$Sr$_{1.5}$MnO$_4$ observed with resonant inelastic x-ray scattering

(2012)

Authors:

X Liu, TF Seman, KH Ahn, Michel van Veenendaal, D Casa, D Prabhakaran, AT Boothroyd, H Ding, JP Hill
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Strongly momentum-dependent screening dynamics in La$_{0.5}$Sr$_{1.5}$MnO$_4$ observed with resonant inelastic x-ray scattering

ArXiv 1210.6634 (2012)

Authors:

X Liu, TF Seman, KH Ahn, Michel van Veenendaal, D Casa, D Prabhakaran, AT Boothroyd, H Ding, JP Hill

Abstract:

We report strongly momentum-dependent local charge screening dynamics in CE-type charge, orbital, and spin ordered La$_{0.5}$Sr$_{1.5}$MnO$_4$, based on Mn K-edge resonant inelastic x-ray scattering data. Through a comparison with theoretical calculations, we show that the observed momentum dependence reflects highly localized, nearest neighbor screening of the transient local charge perturbation in this compound with an exciton-like screening cloud, rather than delocalized screening. The size of the screening cloud is estmated to be about 0.4-0.5 interatomic distances.
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