E. Nazaretski - Academia.edu (original) (raw)
Papers by E. Nazaretski
Solid State Communications, 2015
ABSTRACT We report the influence of two-band superconductivity on the flux creep and the critical... more ABSTRACT We report the influence of two-band superconductivity on the flux creep and the critical current densities of a MgB2 thin film. The small magnetic penetration depth of λ=50±10 nm at T=4 K is related to a clean π-band. We find a high self-field critical current density Jc, which is strongly reduced with applied magnetic field, and attribute this to suppression of the superconductivity in the π-band. The temperature dependence of the creep rate S (T) at low magnetic field can be explained by a simple Anderson–Kim mechanism. The system shows high pinning energies at low field that are strongly suppressed by high field.
Journal of Low Temperature Physics
ABSTRACT
We have investigated the ferrimagnetic domain structure in a Gd{sub 0.67}Ca{sub 0.33}MnOâ thin fi... more We have investigated the ferrimagnetic domain structure in a Gd{sub 0.67}Ca{sub 0.33}MnOâ thin film using magnetic force microscopy. We observe clear signs of phase separation, with magnetic islands embedded in a non-magnetic matrix. We also directly visualize the reversal of magnetization of ferrimagnetic domains as a function of temperature and attribute it to a change in the balance of magnetization of anti-aligned Mn and Gd sublattices.
Extracting quantitative information from magnetic force microscopy has long been considered a dif... more Extracting quantitative information from magnetic force microscopy has long been considered a difficult problem. We present a method to extract a numerical value of the penetration depth utilizing detailed knowledge of the MFM tip properties. Modeling the vortex field as that of a magnetic monopole we use the experimental data on a Nb film to find a penetration depth that is in good agreement with SQUID magnetometer measurements. We discuss the influence of tip geometry on the extracted values of the penetration depth and explore the differences between the simple model of the vortex field and a detailed calculation in the London model.
We compare micromagnetic modeling of Ferromagnetic Resonance (FMR) excitations in thin ferromagne... more We compare micromagnetic modeling of Ferromagnetic Resonance (FMR) excitations in thin ferromagnetic samples in the presence of a nonuniform magnetic field to our FMR data obtained with Magnetic Resonance Force Microscopy (MRFM). MRFM is a novel scanned probe technique based on mechanical detection of magnetic resonance. Its extreme sensitivity originates partially from the high magnetic field gradient of the MRFM probe micromagnet. The presence of the high field gradient imposes unusual conditions on the FMR resonance in the sample under investigation. We will discuss their manifestations in both simulations and experimental data.
Magnetic resonance force microscopy spectra of a 50 nm thick permalloy film were measured as a fu... more Magnetic resonance force microscopy spectra of a 50 nm thick permalloy film were measured as a function of the probe-sample distance and the angle between the film plane and the direction of the externally applied magnetic field. At larger angles the multiple resonance modes were observed at small probe-sample distances. Micromagnetic simulations which include the inhomogeneous magnetic field of the probe tip reveal the localized nature of the exited resonance modes, opening a way to spatially resolved ferromagnetic resonance measurements in a continuous ferromagnetic media.
Magnetic Resonance Force Microscopy (MRFM) is a novel scanned probe technique based on mechanical... more Magnetic Resonance Force Microscopy (MRFM) is a novel scanned probe technique based on mechanical detection of magnetic resonance. Its extreme sensitivity originates partially from the high magnetic field gradient of MRFM probe micromagnet which couples the MRFM probe to the magnetic moments in the sample. We report micromagnetic modeling of Ferromagnetic Resonance (FMR) performed in the local field of the micromagnetic MRFM probe: its strongly inhomogeneous field enables the excitation of localized FMR modes in the sample. This unusual effect provides a mechanism for spatially resolved FMR investigations of ferromagnetic systems. We discuss spatial resolution and results for both quasi 2D and 1D systems.
Reliability, Packaging, Testing, and Characterization of MOEMS/MEMS, Nanodevices, and Nanomaterials XIII, 2014
ABSTRACT Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced... more ABSTRACT Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal conductivity when compared to bulk samples. Measurements of nanofibers' thermal conductivity is challenging since it involves sophisticated sample preparation methods. In this work, we present a novel method suitable for measurements of thermal conductivity in a single nanofiber. A microelectro-mechanical (MEMS) device has been designed and fabricated to perform thermal conductivity measurements on a single nanofiber. A special Si template was designed to collect and transfer individual nanofibers onto a MEMS device. Pt was deposited by Focused Ion Beam to reduce the effective length of a prepared nanofiber. A single La0.95Sr0.05CoO3 nanofiber with a diameter of 140 nm was studied and characterized using this approach. Measured thermal conductivity of a nanofiber was determined to be 0.7 W/m∙K, which is 23% of the value reported for bulk La0.95Sr0.05CoO3 samples.
Journal of synchrotron radiation, 2014
A rotational stage is a key component of every X-ray instrument capable of providing tomographic ... more A rotational stage is a key component of every X-ray instrument capable of providing tomographic or diffraction measurements. To perform accurate three-dimensional reconstructions, runout errors due to imperfect rotation (e.g. circle of confusion) must be quantified and corrected. A dedicated instrument capable of full characterization and circle of confusion mapping in rotary stages down to the sub-10 nm level has been developed. A high-stability design, with an array of five capacitive sensors, allows simultaneous measurements of wobble, radial and axial displacements. The developed instrument has been used for characterization of two mechanical stages which are part of an X-ray microscope.
Spin echo experiments were performed on He immersed in Pt powder (particle size &3 m, 40% packing... more Spin echo experiments were performed on He immersed in Pt powder (particle size &3 m, 40% packing) and 96.5% aerogel. At saturated vapor pressure and "elds of 29 and 70 mT the temperature (8}150 mK) and "eld gradient (2}8 mT/cm) dependences of the transverse spin di!usion coe$cient D , were investigated. Above &80 mK D , varied with ¹\ and was the same for geometrically restricted and bulk He. However, at lower temperatures D , varied more weakly with temperature. At 10 mK, D , "2;10\ (cm/s) was measured for the Pt and 5;10\ for the aerogel sample, respectively. These results are compared with D , values obtained in a "eld of 1 T on He immersed in TmH powder of 10 m particle size.
ABSTRACT The scientists and engineers at Argonne and Brookhaven are collaborating to develop a ne... more ABSTRACT The scientists and engineers at Argonne and Brookhaven are collaborating to develop a new nanopositioning system for the NSLS‐II Hard X‐ray Nanoprobe. In this paper we present the design and development of an advanced sample‐scanning stage system prototype for an MLL‐based hard x‐ray nanoprobe. The design and prototyping activities for the Brookhaven NSLS‐II nanopositioning system will also benefit the ongoing development of the Argonne CNM∕APS MLL‐based hard x‐ray nanoprobe with hard x‐ray focusing in the nanometer scale.
Scientific reports, 2013
The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone ... more The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized with X-rays using ptychography method. The reconstructed probe shows a full-width-at-half-maximum (FWHM) peak size of 11.2 nm. The obtained X-ray wavefront shows excellent agreement with the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures the MLL capable of producing a diffraction-limited focus while offering a sufficient working distance. This achievement opens up opportunities of incorporating a variety of in-situ experiments into ultra high-resolution X-ray microscopy studies.
Nano Research, 2014
Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal ... more Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal conductivity when compared to bulk samples. Measurements of nanofibers' thermal conductivity is challenging since it involves sophisticated sample preparation methods. In this work, we present a novel method suitable for measurements of thermal conductivity of a single nanofiber. A microelectromechanical (MEMS) device has been designed and fabricated to perform thermal conductivity measurements on a single nanofiber. A special Si template was designed to collect and transfer individual nanofibers onto a MEMS device. Pt was deposited by a focused ion beam to reduce the effective length of a prepared nanofiber. La 0.95 Sr 0.05 CoO 3 nanofibers with diameters of 140 nm and 290 nm were studied and characterized using this approach at room temperature. Measured thermal conductivities yielded values of 0.7 W·m -1 ·K -1 and 2.1 W·m -1 ·K -1 , respectively. Our measurements in La 0.95 Sr 0.05 CoO 3 nanofibers confirmed that a decrease of linear dimensions has a profound effect on its thermal conductivity.
Review of Scientific Instruments, 2013
We have constructed a compact prototype apparatus for active correction of circle of confusion du... more We have constructed a compact prototype apparatus for active correction of circle of confusion during rotational motion. Our system combines fiber optic interferometry as a sensing element, the reference cylinder along with the nanopositioning system, and a robust correction algorithm. We demonstrate dynamic correction of run-out errors down to 40 nm; the resolution is limited by ambient environment and accuracy of correcting nanopositioners. Our approach provides a compact solution for in-vacuum scanning nanotomography x-ray experiments with a potential to reach sub-nm level of correction.
Journal of Physics: Conference Series, 2013
ABSTRACT A multilayer Laue lens (MLL) test bed was designed at the Argonne National Laboratory fo... more ABSTRACT A multilayer Laue lens (MLL) test bed was designed at the Argonne National Laboratory for the National Synchrotron Light Source-II (NSLS-II) project at Brookhaven National Laboratory. Argonne and Brookhaven scientists and engineers collaborated to carry out this work in order to achieve NSLS-II's R&D goals of 10-nm focusing of hard x-rays. The test-bed design was based on the experience gained from the Argonne nanopositioning system designed for the CNM/APS hard x-ray nanoprobe project and an MLL test bed at Advanced Photon Source (APS) beamline 26-ID [1-3]. Optomechanical design of the MLL test bed, as well as the preliminary test results for the alignment apparatus and sample base stages' mechanical vibration performances are presented in this paper.
Solid State Communications, 2015
ABSTRACT We report the influence of two-band superconductivity on the flux creep and the critical... more ABSTRACT We report the influence of two-band superconductivity on the flux creep and the critical current densities of a MgB2 thin film. The small magnetic penetration depth of λ=50±10 nm at T=4 K is related to a clean π-band. We find a high self-field critical current density Jc, which is strongly reduced with applied magnetic field, and attribute this to suppression of the superconductivity in the π-band. The temperature dependence of the creep rate S (T) at low magnetic field can be explained by a simple Anderson–Kim mechanism. The system shows high pinning energies at low field that are strongly suppressed by high field.
Journal of Low Temperature Physics
ABSTRACT
We have investigated the ferrimagnetic domain structure in a Gd{sub 0.67}Ca{sub 0.33}MnOâ thin fi... more We have investigated the ferrimagnetic domain structure in a Gd{sub 0.67}Ca{sub 0.33}MnOâ thin film using magnetic force microscopy. We observe clear signs of phase separation, with magnetic islands embedded in a non-magnetic matrix. We also directly visualize the reversal of magnetization of ferrimagnetic domains as a function of temperature and attribute it to a change in the balance of magnetization of anti-aligned Mn and Gd sublattices.
Extracting quantitative information from magnetic force microscopy has long been considered a dif... more Extracting quantitative information from magnetic force microscopy has long been considered a difficult problem. We present a method to extract a numerical value of the penetration depth utilizing detailed knowledge of the MFM tip properties. Modeling the vortex field as that of a magnetic monopole we use the experimental data on a Nb film to find a penetration depth that is in good agreement with SQUID magnetometer measurements. We discuss the influence of tip geometry on the extracted values of the penetration depth and explore the differences between the simple model of the vortex field and a detailed calculation in the London model.
We compare micromagnetic modeling of Ferromagnetic Resonance (FMR) excitations in thin ferromagne... more We compare micromagnetic modeling of Ferromagnetic Resonance (FMR) excitations in thin ferromagnetic samples in the presence of a nonuniform magnetic field to our FMR data obtained with Magnetic Resonance Force Microscopy (MRFM). MRFM is a novel scanned probe technique based on mechanical detection of magnetic resonance. Its extreme sensitivity originates partially from the high magnetic field gradient of the MRFM probe micromagnet. The presence of the high field gradient imposes unusual conditions on the FMR resonance in the sample under investigation. We will discuss their manifestations in both simulations and experimental data.
Magnetic resonance force microscopy spectra of a 50 nm thick permalloy film were measured as a fu... more Magnetic resonance force microscopy spectra of a 50 nm thick permalloy film were measured as a function of the probe-sample distance and the angle between the film plane and the direction of the externally applied magnetic field. At larger angles the multiple resonance modes were observed at small probe-sample distances. Micromagnetic simulations which include the inhomogeneous magnetic field of the probe tip reveal the localized nature of the exited resonance modes, opening a way to spatially resolved ferromagnetic resonance measurements in a continuous ferromagnetic media.
Magnetic Resonance Force Microscopy (MRFM) is a novel scanned probe technique based on mechanical... more Magnetic Resonance Force Microscopy (MRFM) is a novel scanned probe technique based on mechanical detection of magnetic resonance. Its extreme sensitivity originates partially from the high magnetic field gradient of MRFM probe micromagnet which couples the MRFM probe to the magnetic moments in the sample. We report micromagnetic modeling of Ferromagnetic Resonance (FMR) performed in the local field of the micromagnetic MRFM probe: its strongly inhomogeneous field enables the excitation of localized FMR modes in the sample. This unusual effect provides a mechanism for spatially resolved FMR investigations of ferromagnetic systems. We discuss spatial resolution and results for both quasi 2D and 1D systems.
Reliability, Packaging, Testing, and Characterization of MOEMS/MEMS, Nanodevices, and Nanomaterials XIII, 2014
ABSTRACT Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced... more ABSTRACT Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal conductivity when compared to bulk samples. Measurements of nanofibers' thermal conductivity is challenging since it involves sophisticated sample preparation methods. In this work, we present a novel method suitable for measurements of thermal conductivity in a single nanofiber. A microelectro-mechanical (MEMS) device has been designed and fabricated to perform thermal conductivity measurements on a single nanofiber. A special Si template was designed to collect and transfer individual nanofibers onto a MEMS device. Pt was deposited by Focused Ion Beam to reduce the effective length of a prepared nanofiber. A single La0.95Sr0.05CoO3 nanofiber with a diameter of 140 nm was studied and characterized using this approach. Measured thermal conductivity of a nanofiber was determined to be 0.7 W/m∙K, which is 23% of the value reported for bulk La0.95Sr0.05CoO3 samples.
Journal of synchrotron radiation, 2014
A rotational stage is a key component of every X-ray instrument capable of providing tomographic ... more A rotational stage is a key component of every X-ray instrument capable of providing tomographic or diffraction measurements. To perform accurate three-dimensional reconstructions, runout errors due to imperfect rotation (e.g. circle of confusion) must be quantified and corrected. A dedicated instrument capable of full characterization and circle of confusion mapping in rotary stages down to the sub-10 nm level has been developed. A high-stability design, with an array of five capacitive sensors, allows simultaneous measurements of wobble, radial and axial displacements. The developed instrument has been used for characterization of two mechanical stages which are part of an X-ray microscope.
Spin echo experiments were performed on He immersed in Pt powder (particle size &3 m, 40% packing... more Spin echo experiments were performed on He immersed in Pt powder (particle size &3 m, 40% packing) and 96.5% aerogel. At saturated vapor pressure and "elds of 29 and 70 mT the temperature (8}150 mK) and "eld gradient (2}8 mT/cm) dependences of the transverse spin di!usion coe$cient D , were investigated. Above &80 mK D , varied with ¹\ and was the same for geometrically restricted and bulk He. However, at lower temperatures D , varied more weakly with temperature. At 10 mK, D , "2;10\ (cm/s) was measured for the Pt and 5;10\ for the aerogel sample, respectively. These results are compared with D , values obtained in a "eld of 1 T on He immersed in TmH powder of 10 m particle size.
ABSTRACT The scientists and engineers at Argonne and Brookhaven are collaborating to develop a ne... more ABSTRACT The scientists and engineers at Argonne and Brookhaven are collaborating to develop a new nanopositioning system for the NSLS‐II Hard X‐ray Nanoprobe. In this paper we present the design and development of an advanced sample‐scanning stage system prototype for an MLL‐based hard x‐ray nanoprobe. The design and prototyping activities for the Brookhaven NSLS‐II nanopositioning system will also benefit the ongoing development of the Argonne CNM∕APS MLL‐based hard x‐ray nanoprobe with hard x‐ray focusing in the nanometer scale.
Scientific reports, 2013
The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone ... more The focusing performance of a multilayer Laue lens (MLL) with 43.4 μm aperture, 4 nm finest zone width and 4.2 mm focal length at 12 keV was characterized with X-rays using ptychography method. The reconstructed probe shows a full-width-at-half-maximum (FWHM) peak size of 11.2 nm. The obtained X-ray wavefront shows excellent agreement with the dynamical calculations, exhibiting aberrations less than 0.3 wave period, which ensures the MLL capable of producing a diffraction-limited focus while offering a sufficient working distance. This achievement opens up opportunities of incorporating a variety of in-situ experiments into ultra high-resolution X-ray microscopy studies.
Nano Research, 2014
Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal ... more Thermoelectric oxide nanofibers prepared by electrospinning are expected to have reduced thermal conductivity when compared to bulk samples. Measurements of nanofibers' thermal conductivity is challenging since it involves sophisticated sample preparation methods. In this work, we present a novel method suitable for measurements of thermal conductivity of a single nanofiber. A microelectromechanical (MEMS) device has been designed and fabricated to perform thermal conductivity measurements on a single nanofiber. A special Si template was designed to collect and transfer individual nanofibers onto a MEMS device. Pt was deposited by a focused ion beam to reduce the effective length of a prepared nanofiber. La 0.95 Sr 0.05 CoO 3 nanofibers with diameters of 140 nm and 290 nm were studied and characterized using this approach at room temperature. Measured thermal conductivities yielded values of 0.7 W·m -1 ·K -1 and 2.1 W·m -1 ·K -1 , respectively. Our measurements in La 0.95 Sr 0.05 CoO 3 nanofibers confirmed that a decrease of linear dimensions has a profound effect on its thermal conductivity.
Review of Scientific Instruments, 2013
We have constructed a compact prototype apparatus for active correction of circle of confusion du... more We have constructed a compact prototype apparatus for active correction of circle of confusion during rotational motion. Our system combines fiber optic interferometry as a sensing element, the reference cylinder along with the nanopositioning system, and a robust correction algorithm. We demonstrate dynamic correction of run-out errors down to 40 nm; the resolution is limited by ambient environment and accuracy of correcting nanopositioners. Our approach provides a compact solution for in-vacuum scanning nanotomography x-ray experiments with a potential to reach sub-nm level of correction.
Journal of Physics: Conference Series, 2013
ABSTRACT A multilayer Laue lens (MLL) test bed was designed at the Argonne National Laboratory fo... more ABSTRACT A multilayer Laue lens (MLL) test bed was designed at the Argonne National Laboratory for the National Synchrotron Light Source-II (NSLS-II) project at Brookhaven National Laboratory. Argonne and Brookhaven scientists and engineers collaborated to carry out this work in order to achieve NSLS-II's R&D goals of 10-nm focusing of hard x-rays. The test-bed design was based on the experience gained from the Argonne nanopositioning system designed for the CNM/APS hard x-ray nanoprobe project and an MLL test bed at Advanced Photon Source (APS) beamline 26-ID [1-3]. Optomechanical design of the MLL test bed, as well as the preliminary test results for the alignment apparatus and sample base stages' mechanical vibration performances are presented in this paper.