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The question of how bulk electronic order is terminated at a surface is an intriguing one, and one with possible practical implications—for example in nanoscaled systems that may be characterized by their surface behaviour. One example of such order is orbital order, and in principle it should be possible to probe the termination of this order with surface X-ray scattering. Here, we report the first observation of the scattering arising from the termination of bulk orbital order at the surface of a crystal—so-called ‘orbital truncation rods’. The measurements, carried out on a cleaved perovskite, La0.5Sr1.5MnO4, reveal that whereas the crystallographic surface is atomically smooth, the orbital ‘surface’, which is observed through the atomic displacements caused by the orbital order, is much rougher, with a typical scale of the surface roughness of ∼7 Å. Interestingly, the temperature dependence of this scattering shows evidence of a surface-induced second-order transition. [ABSTRACT FROM AUTHOR]

We report on the development of a circularly polarized x-ray microprobe in the intermediate energy range from 5 to 10 keV. In this experiment linearly polarized synchrotron radiation was circularly polarized by means of a Bragg-diffracting diamond phase retarder and subsequently focused down to a spot size of about 4x2 μm[sup 2] by a Fresnel zone plate. The properties of the microprobe were characterized, and the technique was applied to the two-dimensional mapping of magnetic domains in HoFe[sub 2]. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We have used a combination of resonant magnetic x-ray scattering and x-ray absorption spectroscopy to investigate the properties of the doped spin-orbital Mott insulator Sr2Ir1−xRhxO4 (0.07≤x≤0.70). We show that Sr2Ir1−xRhxO4 represents a unique model system for the study of dilute magnetism in the presence of strong spin-orbit coupling, and provide evidence of a doping-induced change in magnetic structure and a suppression of magnetic order at xc∼0.17. We demonstrate that Rh-doping introduces Rh3+/Ir5+ ions which effectively hole-dope this material. We propose that the magnetic phase diagram for this material can be understood in terms of a novel spin-orbital percolation picture. [ABSTRACT FROM AUTHOR]