Alexei Grigoriev
University of Wisconsin-Madison
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Publication
Featured researches published by Alexei Grigoriev.
Applied Physics Letters | 2006
Alexei Grigoriev; Dal-Hyun Do; Dong-Min Kim; Chang-Beom Eom; Paul G. Evans; Bernhard W. Adams; Eric M. Dufresne
We report an ultrafast piezoelectric switch for synchrotron x rays. A thin epitaxial film of piezoelectric Pb(Zr,Ti)O3 works as a diffractive optical switch at frequencies from dc to >1GHz. The broad frequency range allows single bunches of synchrotron x rays to be selected in an arbitrary sequence. The piezoelectric effect introduces mechanical strains of a fraction of 1% in the Pb(Zr,Ti)O3 film, which can be used for blocking or passing diffracted x rays.
Integrated Ferroelectrics | 2008
Dal-Hyun Do; Alexei Grigoriev; Dong-Min Kim; Chang-Beom Eom; Paul G. Evans; Eric M. Dufresne
ABSTRACT Probing the piezoelectricity and ferroelectricity of thin film devices and nanostructures quantitatively has proven to be challenging because the appropriate experimental tools have had a limited range of usefulness. We show here that the piezoelectric and ferroelectric properties of epitaxial thin films can be measured quantitatively using time-resolved synchrotron x-ray microdiffraction. Microdiffraction combines structural specificity with the appropriate spatial resolution and ability to probe structures with electrical contacts. Our measurements of piezoelectric coefficients and coercive electric fields for Pb(Zr,Ti)O3 capacitors using this approach are in excellent quantitative agreement with results obtained electrically and mechanically. The time and spatial resolution of microdiffraction probes are well-defined and decoupled from electrical and mechanical resonances of the ferroelectric capacitor.
Applied Physics Letters | 2010
Rebecca J. Sichel; Alexei Grigoriev; Dal-Hyun Do; Seung-Hyub Baek; Ho Won Jang; C. M. Folkman; Chang-Beom Eom; Zhonghou Cai; Paul G. Evans
Epitaxial BiFeO3 thin films on miscut (001) SrTiO3 substrates relax via mechanisms leading to an average rotation of the crystallographic axes of the BiFeO3 layer with respect to the substrate. The angle of the rotation reaches a maximum in the plane defined by the surface normal of the film and the direction of the surface miscut. X-ray microdiffraction images show that each BiFeO3 mosaic block is rotated by a slightly different angle and contains multiple polarization domains. These effects lead to a complicated overall symmetry in BiFeO3 thin films. This relaxation mechanism can be extended to other complex oxides.
Review of Scientific Instruments | 2007
Alexei Grigoriev; Dal-Hyun Do; Paul G. Evans; Bernhard W. Adams; Eric C. Landahl; Eric M. Dufresne
Time scales of long-range physical processes in solids are typically in the range of picoseconds to nanoseconds. These times are commensurate with the time resolution of structural probes based on modern synchrotron x-ray sources. Several processes of technological and scientific interest can be driven by applied electric fields, but synchronizing electrically driven phenomena with an x-ray probe poses a technical challenge. We describe the synchronization of a well-defined number of fast electrical pulses with the time structure of synchrotron x rays to probe the dynamics of thin films and nanostructures. This synchronization technique yields x-ray transient signals with 600 ps transitions in ferroelectric thin films, with a contribution of approximately 320 ps due to timing jitter in the synchronization.
Review of Scientific Instruments | 2011
Alexei Grigoriev; Mandana Meisami Azad; John McCampbell
We have developed a new approach to measure fast electrical signals during polarization switching in ferroelectric thin-film capacitors. This article describes a simple method for probing transient currents and voltages in a broad range of time scales from microseconds to hundreds of picoseconds. In order to test our approach, we probed polarization dynamics in commercial PbZr(0.2)Ti(0.8)O(3) ferroelectric capacitors in which the measured switching time was as fast as 1.7 ns.
Integrated Ferroelectrics | 2006
Alexei Grigoriev; Dal-Hyun Do; Dong-Min Kim; Chang-Beom Eom; Paul G. Evans; Bernhard W. Adams; Eric M. Dufresne
ABSTRACT As the polarization of a ferroelectric thin film reverses in response to an applied electric field, concomitant structural changes can be visualized using time-resolved x-ray microdiffraction. We report the details of this visualization approach and discuss the structural signature of polarization switching measured by time-resolved x-ray diffraction.
MRS Proceedings | 2005
Alexei Grigoriev; Dal-Hyun Do; Dong-Min Kim; Chang-Beom Eom; Bernhard W. Adams; Eric M. Dufresne; Paul G. Evans
When an electric field is applied to a ferroelectric the crystal lattice spacing changes as a result of the converse piezoelectric effect. Although the piezoelectric effect and polarization switching have been investigated for decades there has been no direct nanosecond-scale visualization of these phenomena in solid crystalline ferroelectrics. Synchrotron x-rays allow the polarization switching and the crystal lattice distortion to be visualized in space and time on scales of hundreds of nanometers and hundreds of picoseconds using ultrafast x-ray microdiffraction. Here we report the polarization switching visualization and polarization domain wall velocities for Pb(Zr0.45Ti0.55)O3 thin film ferroelectric capacitors studied by timeresolved x-ray microdiffraction.
Physical Review Letters | 2006
Alexei Grigoriev; Dal-Hyun Do; Dong-Min Kim; Chang-Beom Eom; Bernhard W. Adams; Eric M. Dufresne; Paul G. Evans
Physical Review Letters | 2008
Alexei Grigoriev; Rebecca J. Sichel; Ho Nyung Lee; Eric C. Landahl; Bernhard W. Adams; Eric M. Dufresne; Paul G. Evans
Physical Review B | 2009
Alexei Grigoriev; Rebecca J. Sichel; Ji Young Jo; S. Choudhury; Long-Qing Chen; Ho Nyung Lee; Eric C. Landahl; Bernhard W. Adams; Eric M. Dufresne; Paul G. Evans