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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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The J eff=1/2 insulator Sr 3Ir 2O 7 studied by means of angle-resolved photoemission spectroscopy

Journal of Physics Condensed Matter 24:41 (2012)

Authors:

BM Wojek, MH Berntsen, S Boseggia, AT Boothroyd, D Prabhakaran, DF McMorrow, HM Ronnow, J Chang, O Tjernberg

Abstract:

The low-energy electronic structure of the J eff=1/2 spinorbit insulator Sr 3Ir 2O 7 has been studied by means of angle-resolved photoemission spectroscopy. A comparison of the results for bilayer Sr 3Ir 2O 7 with available literature data for the related single-layer compound Sr2IrO4 reveals qualitative similarities and similar J eff=1/2 bandwidths for the two materials, but also pronounced differences in the distribution of the spectral weight. In particular, photoemission from the J eff=1/2 states appears to be suppressed. Yet, it is found that the Sr 3Ir 2O 7 data are in overall better agreement with band-structure calculations than the data for Sr 2IrO 4. © 2012 IOP Publishing Ltd.
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The Jeff = 1/2 insulator Sr3Ir2O7 studied by means of angle-resolved photoemission spectroscopy.

J Phys Condens Matter 24:41 (2012) 415602

Authors:

BM Wojek, MH Berntsen, S Boseggia, AT Boothroyd, D Prabhakaran, DF McMorrow, HM Rønnow, J Chang, O Tjernberg

Abstract:

The low-energy electronic structure of the J(eff) = 1/2 spin-orbit insulator Sr3Ir2O7 has been studied by means of angle-resolved photoemission spectroscopy. A comparison of the results for bilayer Sr3Ir2O7 with available literature data for the related single-layer compound Sr2IrO4 reveals qualitative similarities and similar J(eff) = 1/2 bandwidths for the two materials, but also pronounced differences in the distribution of the spectral weight. In particular, photoemission from J(eff) = 1/2 the states appears to be suppressed. Yet, it is found that the Sr3Ir2O7 data are in overall better agreement with band-structure calculations than the data for Sr2IrO4.
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Dynamic disorder and the α-β phase transition in quartz-type FePO4 at high temperature investigated by total neutron scattering, Raman spectroscopy, and density functional theory

Physical Review B American Physical Society (APS) 86:13 (2012) 134104

Authors:

GM Bhalerao, P Hermet, J Haines, O Cambon, DA Keen, MG Tucker, E Buixaderas, P Simon
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LiTaO3 crystals with near-zero birefringence

Journal of Applied Crystallography 45:5 (2012) 1030-1037

Authors:

AM Glazer, N Zhang, A Bartasyte, DS Keeble, S Huband, PA Thomas, I Gregora, F Borodavka, S Margueron, J Hlinka

Abstract:

A study of vapour transport equilibrated crystals of LiTaO3 shows periodic fringes that change with temperature. The origin of these fringes and their behaviour is explained in terms of domains with slanted walls. Micro-Raman measurements have been used to determine the Li2O concentration through the crystals, and by comparison with the observed fringe pattern the variation of birefringence with Li2O content has been determined.
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