T. dos Santos Rolo
Karlsruhe Institute of Technology
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Publication
Featured researches published by T. dos Santos Rolo.
Nature Communications | 2017
Dmitry Karpov; Zhen Liu; T. dos Santos Rolo; Ross Harder; Prasanna V. Balachandran; Dezhen Xue; Turab Lookman; E. Fohtung
Topological defects of spontaneous polarization are extensively studied as templates for unique physical phenomena and in the design of reconfigurable electronic devices. Experimental investigations of the complex topologies of polarization have been limited to surface phenomena, which has restricted the probing of the dynamic volumetric domain morphology in operando. Here, we utilize Bragg coherent diffractive imaging of a single BaTiO3 nanoparticle in a composite polymer/ferroelectric capacitor to study the behavior of a three-dimensional vortex formed due to competing interactions involving ferroelectric domains. Our investigation of the structural phase transitions under the influence of an external electric field shows a mobile vortex core exhibiting a reversible hysteretic transformation path. We also study the toroidal moment of the vortex under the action of the field. Our results open avenues for the study of the structure and evolution of polar vortices and other topological structures in operando in functional materials under cross field configurations.Imaging of topological states of matter such as vortex configurations has generally been limited to 2D surface effects. Here Karpov et al. study the volumetric structure and dynamics of a vortex core mediated by electric-field induced structural phase transition in a ferroelectric BaTiO3 nanoparticle.
Journal of Physics: Conference Series | 2013
Y Cheng; V Altapova; Lukas Helfen; Feng Xu; T. dos Santos Rolo; Patrik Vagovič; M. Fiederle; Tilo Baumbach
X-ray computed laminography has been developed as a non-destructive imaging technique for inspecting laterally extended objects. Benefiting from a parallel-beam geometry, high photon flux of synchrotron sources and modern high-resolution detector systems, synchrotron radiation computed laminography (SRCL) results in a powerful three-dimensional microscopy technique. SRCL can be combined with different contrast modes, such as absorption, phase and dark-field contrasts, in order to provide complementary information for the same specimen. Here we show the development of SRCL at the TopoTomo beamline of the ANKA light source. A novel instrumentation design is reported and compared to the existing one. For this design, experimental results from different contrast modalities are shown.
nuclear science symposium and medical imaging conference | 2010
D. Greiffenberg; Angelica Cecilia; A. Zwerger; A. Fauler; Patrik Vagovič; J. Butzer; Elias Hamann; T. dos Santos Rolo; Tilo Baumbach; M. Fiederle
CdTe is a promising sensor material for the detection of γ-Rays and X-Rays as it offers an absorption efficiency higher than 50 % for photon energies up to 120 keV for 1 mm thick sensors. Connected to the pixilated, single-photon counting readout electronics Timepix, its application at a synchrotron source was investigated. The focus of the investigations was on the high flux behavior of the CdTe-Timepix assemblies, as CdTe is known to suffer from a degradation of the count-rates when being illuminated with high photon fluxes. Moreover, the high flux behavior of the readout electronics itself was investigated by measuring an assembly with a silicon sensor, which is not known to suffer from a degradation effect at high photon fluxes.
ieee nuclear science symposium | 2008
D. Greiffenberg; Angelica Cecilia; A. Zwerger; A. Fauler; T. dos Santos Rolo; D. Pelliccia; Patrik Vagovič; R. Simon; Tilo Baumbach; Michael Fiederle
Medipix2 assemblies with CdTe sensors have been characterized using synchrotron radiation. Processing of the assemblies has been done at the Freiburg material research center (FMF), the characterization has been performed at the ANKA at the Forschungszentrum Karlsruhe. The following paper reports the first results of the research of efficient pixelarray detectors for application in a synchrotron providing high energetic photons. Examinations on the homogeneity of the sensor, charge sharing and an energy scan will be shown.
Journal of Synchrotron Radiation | 2017
Sergey Gasilov; Alberto Mittone; T. dos Santos Rolo; S.N. Polyakov; Sergey Zholudev; Sergey Terentyev; V. D. Blank; Alberto Bravin; Tilo Baumbach
In this work a double-crystal setup is employed to study compound refractive lenses made of single-crystal diamond. The point spread function of the lens is calculated taking into account the lens transmission, the wavefront aberrations, and the ultra-small-angle broadening of the X-ray beam. It is shown that, similarly to the wavefront aberrations, the ultra-small-angle scattering effects can significantly reduce the intensity gain and increase the focal spot size. The suggested approach can be particularly useful for the characterization of refractive X-ray lenses composed of many tens of unit lenses.
Materials Testing-Materials and Components Technology and Application | 2009
Tilo Baumbach; T. dos Santos Rolo; Alexey Ershov; Lukas Helfen; Daniel Lübbert; Peter Modregger; Danielle Pelliccia; Patrik Vagovič; Feng Xu
Kurzfassung Mikrotomographie erlaubt die hochauflösende Abbildung verdeckter Mikrostrukturen und den Nachweis von Mikrorissen und Mikroporen in vielfältigen Bereichen, darunter die Untersuchung von mikroporösen Materialien und Fasernetzwerken, der Mikrostruktur biokompatibler Materialien (Implantate), der Entwicklung der Struktur von Metallgefügen u.v.m. Synchrotron-Laminographie erweitert das Anwendungsspektrum der 3-D-Methoden auf die zerstörungsfreie Bauteiluntersuchung ohne Probenentnahme bzw. Probenpräparation, und erweitert die hoch auflösende Inspektion z.B. in der Mikrosystemtechnik, der Paläontologie Archäologie etc. Ultraschnelle Radiographie, Computertomographie und Laminographie erlauben die In-situ-Untersuchung von Proben und Bauteilen in Echtzeit und unter betriebsnahen Bedingungen verschiedenster Probenumgebung. Phasenkontrast erweitert die Anwendungsbreite der 2-D und 3-D abbildenden Synchrotronverfahren auf leichte Materialien und führte die Methoden damit in die Leichtbautechnologien und die Lebenswissenschaften. Die Kombination der Techniken mit Röntgenoptiken treibt die Grenzen der Ortsauflösung in den Bereich weniger 10 nm.
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment | 2011
Angelica Cecilia; Alexander Rack; Paul-Antoine Douissard; Thierry Martin; T. dos Santos Rolo; Patrik Vagovič; Elias Hamann; T. van de Kamp; Alexander Riedel; Michael Fiederle; Tilo Baumbach
Journal of Synchrotron Radiation | 2016
Matthias Vogelgesang; Tomas Farago; Thilo F. Morgeneyer; Lukas Helfen; T. dos Santos Rolo; Anton Myagotin; Tilo Baumbach
Journal of Crystal Growth | 2011
J. Wittge; Arne Croell; D. Allen; P. McNally; Patrik Vagovič; T. dos Santos Rolo; Z. Li; Tilo Baumbach; E. Gorostegui-Colinas; J. Garagorri; M.R. Elizalde; M.C. Fossati; D.K. Bowen; B. K. Tanner
Physica Status Solidi (a) | 2011
J. Wittge; A. Hess; A. Cröll; Alexander Rack; D. Allen; P. McNally; T. dos Santos Rolo; Patrik Vagovič; Tilo Baumbach; J. Garagorri; M.R. Elizalde; B. K. Tanner