Showing 1–7 of 7 results for author: Livet, F

High resolution strain measurements in highly disordered materials

Authors: Mark Sutton, J. R. M. Lhermitte, F. Livet, F. Ehrburger-Dolle

Abstract: The ability to measure small deformations or strains is useful for understanding many aspects of materials. Here, a new analysis of speckle diffraction peaks is presented in which the systematic shifts of the speckles are analyzed allowing for strain (or flow) patterns to be inferred. This speckle tracking technique measures strain patterns with a accuracy similar to x-ray single crystal measureme… ▽ More The ability to measure small deformations or strains is useful for understanding many aspects of materials. Here, a new analysis of speckle diffraction peaks is presented in which the systematic shifts of the speckles are analyzed allowing for strain (or flow) patterns to be inferred. This speckle tracking technique measures strain patterns with a accuracy similar to x-ray single crystal measurements but in amorphous or highly disordered materials. △ Less

Submitted 28 December, 2020; v1 submitted 27 April, 2020; originally announced April 2020.

Journal ref: Phys. Rev. Research 3, 013119 (2021)

Combined coherent x-ray micro-diffraction and local mechanical loading on copper nanocrystals

Authors: G. Beutier, M. Verdier, M. De Boissieu, B. Gilles, F. Livet, M. -I. Richard, T. W. Cornelius, S. Labat, O. Thomas

Abstract: Coherent x-ray micro-diffraction and local mechanical loading can be combined to investigate the mechanical deformation in crystalline nanostructures. Here we present measurements of plastic deformation in a copper crystal of sub-micron size obtained by loading the sample with an Atomic Force Microscopy tip. The appearance of sharp features in the diffraction pattern, while conserving its global s… ▽ More Coherent x-ray micro-diffraction and local mechanical loading can be combined to investigate the mechanical deformation in crystalline nanostructures. Here we present measurements of plastic deformation in a copper crystal of sub-micron size obtained by loading the sample with an Atomic Force Microscopy tip. The appearance of sharp features in the diffraction pattern, while conserving its global shape, is attributed to crystal defects induced by the tip. △ Less

Submitted 30 May, 2013; originally announced May 2013.

Journal ref: Journal of Physics: Conference Series 425 (2013) 2003

A coherent way to image dislocations

Authors: V. L. R. Jacques, S. Ravy, D. Le Bolloc'h, E. Pinsolle, M. Sauvage-Simkin, F. Livet

Abstract: The use of coherent x-ray beams has been greatly developing for the past decades. They are now used by a wide scientific community to study biological materials, phase transitions in crystalline materials, soft matter, magnetism, strained structures, or nano-objects. Different kinds of measurements can be carried out: x-ray photon correlation spectroscopy allowing studying dynamics in soft and har… ▽ More The use of coherent x-ray beams has been greatly developing for the past decades. They are now used by a wide scientific community to study biological materials, phase transitions in crystalline materials, soft matter, magnetism, strained structures, or nano-objects. Different kinds of measurements can be carried out: x-ray photon correlation spectroscopy allowing studying dynamics in soft and hard matter, and coherent diffraction imaging enabling to reconstruct the shape and strain of some objects by using methods such as holography or ptychography. In this article, we show that coherent x-ray diffraction (CXRD) brings a new insight in another scientific field: the detection of single phase defects in bulk materials. Extended phase objects such as dislocations embedded in the bulk are usually probed by electron microscopy or X-ray topography. However, electron microscopy is restricted to thin samples, and x-ray topography is resolution-limited. We show here that CXRD brings much more accurate information about dislocation lines (DLs) in bulk samples and opens a route for a better understanding of the fine structure of the core of bulk dislocations. △ Less

Submitted 31 August, 2010; originally announced August 2010.

Comments: Article is 8 pages, with 4 figures and 29 references; 6 pages of additional information together with 4 figures

Spin density wave dislocation in chromium probed by coherent x-ray diffraction

Authors: V. L. R. Jacques, D. Le Bolloc'h, S. Ravy, C. Giles F. Livet, S. B. Wilkins

Abstract: We report on the study of a magnetic dislocation in pure chromium. Coherent x-ray diffraction profiles obtained on the incommensurate Spin Density Wave (SDW) reflection are consistent with the presence of a dislocation of the magnetic order, embedded at a few micrometers from the surface of the sample. Beyond the specific case of magnetic dislocations in chromium, this work may open up a new met… ▽ More We report on the study of a magnetic dislocation in pure chromium. Coherent x-ray diffraction profiles obtained on the incommensurate Spin Density Wave (SDW) reflection are consistent with the presence of a dislocation of the magnetic order, embedded at a few micrometers from the surface of the sample. Beyond the specific case of magnetic dislocations in chromium, this work may open up a new method for the study of magnetic defects embedded in the bulk. △ Less

Submitted 22 October, 2009; originally announced October 2009.

Comments: 8 pages, 7 figures

Journal ref: Eur. Phys. J. B 70 3 (2009) 317-325

Coherent scattering from silicon mocrystal surface

Authors: F. Livet, G. Beutier, M. de Boissieu, S. Ravy, F. Picca, D. Le Bolloc'h, V. Jacques

Abstract: Using coherent x-ray scattering, we evidenced atomic step roughness at the [111] vicinal surface of a silicon monocrystal of 0.05 degree miscut. Close to the (1/2 1/2 1/2) anti-Bragg position of the reciprocal space which is particularly sensitive to the [111] surface, the truncation rod exhibits a contrasted speckle pattern that merges into a single peak closer to the (111) Bragg peak of the bu… ▽ More Using coherent x-ray scattering, we evidenced atomic step roughness at the [111] vicinal surface of a silicon monocrystal of 0.05 degree miscut. Close to the (1/2 1/2 1/2) anti-Bragg position of the reciprocal space which is particularly sensitive to the [111] surface, the truncation rod exhibits a contrasted speckle pattern that merges into a single peak closer to the (111) Bragg peak of the bulk. The elongated shape of the speckles along the[111] direction confirms the monoatomic step sensibility of the technique. This experiment opens the way towards studies of step dynamics on crystalline surfaces. △ Less

Submitted 11 August, 2009; originally announced August 2009.

Comments: Submitted to Physical Review Letters

Observation of correlations up to the micrometer scale in sliding charge-density waves

Authors: D. Le Bolloc'h, V. L. R. Jacques, N. Kirova, J. Dumas, S. Ravy, J. Marcus, F. Livet

Abstract: High-resolution coherent x-ray diffraction experiment has been performed on the charge density wave (CDW) system K$_{0.3}$MoO$_3$. The $2k_F$ satellite reflection associated with the CDW has been measured with respect to external dc currents. In the sliding regime, the $2k_F$ satellite reflection displays secondary satellites along the chain axis which corresponds to correlations up to the micro… ▽ More High-resolution coherent x-ray diffraction experiment has been performed on the charge density wave (CDW) system K$_{0.3}$MoO$_3$. The $2k_F$ satellite reflection associated with the CDW has been measured with respect to external dc currents. In the sliding regime, the $2k_F$ satellite reflection displays secondary satellites along the chain axis which corresponds to correlations up to the micrometer scale. This super long range order is 1500 times larger than the CDW period itself. This new type of electronic correlation seems inherent to the collective dynamics of electrons in charge density wave systems. Several scenarios are discussed. △ Less

Submitted 8 January, 2008; v1 submitted 27 November, 2007; originally announced November 2007.

Comments: 4 pages, 3 figures Typos added, references removed

Journal ref: Phys. Rev. Lett. 100, 096403 (2008)

Coherent X-ray Scattering from Manganite Charge and Orbital Domains

Authors: C. S. Nelson, J. P. Hill, Doon Gibbs, F. Yakhou, F. Livet, Y. Tomioka, T. Kimura, Y. Tokura

Abstract: We report coherent x-ray scattering studies of charge and orbital domains in manganite systems. The experiments were carried out on LaMnO_3 and Pr_{0.6}Ca_{0.4}MnO_3, with the incident photon energy tuned near the Mn K edge. At room temperature, the orbital speckle pattern of LaMnO_3 was observed to be constant over a timescale of at least minutes, which is indicative of static orbital domains o… ▽ More We report coherent x-ray scattering studies of charge and orbital domains in manganite systems. The experiments were carried out on LaMnO_3 and Pr_{0.6}Ca_{0.4}MnO_3, with the incident photon energy tuned near the Mn K edge. At room temperature, the orbital speckle pattern of LaMnO_3 was observed to be constant over a timescale of at least minutes, which is indicative of static orbital domains on this timescale. For Pr_{0.6}Ca_{0.4}MnO_3, both charge and orbital speckle patterns were observed. The observation of the latter rules out the presence of fast orbital fluctuations, while long time series data-- on the order of several minutes-- were suggestive of slow dynamic behavior. In contrast, the charge order speckle patterns were static. △ Less

Submitted 19 June, 2002; originally announced June 2002.

Comments: 6 pages, 4 figures