Research Highlights Archive
Mesoscopic mechanism of the domain wall interaction with elastic defects in uniaxial ferroelectrics
Anna N. Morozovska, Eugene A. Eliseev, G. S. Svechnikov, and Sergei V. Kalinin
Partial Abstract: The role of elastic defects on the kinetics of 180° uncharged ferroelectric domain wall motion is explored using continuum time-dependent Landau-Ginzburg-Devonshire equation with elastic dipole coupling. In one dimensional case, ripples, steps, and oscillations of the domain wall velocity appear due to the wall-defect interactions.
The time evolution of turbulent parameters in reversed-field pinch plasmas
J. B. Titus, Brandon Alexander, and J. A. Johnson, III
Partial Abstract: Turbulence is abundant in fully ionized fusion plasmas, with unique turbulent characteristics in different phases of the discharge. Using Fourier and chaos-based techniques, a set of parameters have been developed to profile the time evolution of turbulence in high temperature, fusion plasmas, specifically in self-organized, reversed-field pinch plasma in the Madison Symmetric Torus.
Spin transport parameters in metallic multilayers determined by ferromagnetic resonance measurements of spin-pumping
C. T. Boone, Hans T. Nembach, Justin M. Shaw, and T. J. Silva
Partial Abstract: We measured spin-transport in nonferromagnetic (NM) metallic multilayers from the contribution to damping due to spin pumping from a ferromagnetic Co90Fe10 thin film. The multilayer stack consisted of NM1/NM2/Co90Fe10(2 nm)/NM2/NM3 with varying NM materials and thicknesses. Using conventional theory for one-dimensional diffusive spin transport in metals, we show that the effective damping due to spin pumping can be strongly affected by the spin transport properties of each NM in the multilayer, which permits the use of damping measurements to accurately determine the spin transport properties of the various NM layers in the full five-layer stack.
Influence of hydrogen on interstitial iron concentration in multicrystalline silicon during annealing steps
Philipp Karzel, Alexander Frey, Susanne Fritz, and Giso Hahn
Partial Abstract:The influence of in-diffusing atomic H into an annealed multicrystalline silicon wafer on the concentration of interstitial iron [Fei] was investigated. Neighboring wafers with similar initial [Fei] were annealed with and without in-diffusing H.
Tuning graphene morphology by substrate towards wrinkle-free devices: Experiment and simulation
M. Lanza, Y. Wang, A. Bayerl, T. Gao, M. Porti, M. Nafria, H. Liang, G. Jing, Z. Liu, Y. Zhang, Y. Tong, and H. Duan
Partial Abstract:Graphene grown by chemical vapor deposition can be used as the conductive channel in metal oxide semiconductor field effect transistors, metallic electrodes in capacitors, etc. However, substrate-induced corrugations and strain-related wrinkles formed on the graphene layer impoverish the properties of these devices by lowering the conductance and increasing their variability.
What does a first-order reversal curve diagram really mean? A study case: Array of ferromagnetic nanowires
Costin-Ionuţ Dobrotă and Alexandru Stancu
Partial Abstract:The magnetic characterization technique of hysteretic materials based on the measurement of the first-order reversal curves (FORC) is one of the most appealing methods recently introduced in hundreds of new laboratories, but due to the complexity of the FORC data analysis, it is not always properly used. This method originated in identification procedures for the classical Preisach model and consequently often the FORC distribution is interpreted as a slightly distorted Preisach distribution. In this paper, we discuss this idea from two points of view derived from the basic assumptions used in the Preisach model.
Revisiting the mechanisms involved in Line Width Roughness smoothing of 193 nm photoresist patterns during HBr plasma treatment
M. Brihoum, R. Ramos, K. Menguelti, G. Cunge, E. Pargon, and O. Joubert
Partial Abstract:HBr plasma treatments are widely used in nanoscale lithographic technologies to increase the plasma etch resistance of 193 nm photoresist masks as well as to decrease their Line Width Roughness (LWR). VUV irradiation of the photoresist is known to play a major role in this process by inducing polymer chains rearrangement and finally LWR reduction.
Strain assisted inter-diffusion in GaN/AlN quantum dots
C. Leclere, V. Fellmann, C. Bougerol, D. Cooper, B. Gayral, M. G. Proietti, H. Renevier, and B. Daudin
Partial Abstract: The structural and optical properties of high temperature-annealed superlattices of GaN quantum dots embedded in AlN barrier have been studied by a combination of X-ray techniques (reciprocal space mapping, multiwavelength anomalous diffraction, and diffraction anomalous fine structure), high resolution transmission electron microscopy, and photoluminescence spectroscopy. Taking advantage of the disentangling of the chemical and structural information provided by the simultaneous use of X-ray absorption and diffraction data obtained in a synchrotron environment, we provide quantitative determination of strain and composition for each different region of the nanostructures.
Electron current extraction from radio frequency excited micro-dielectric barrier discharges
Jun-Chieh Wang, Napoleon Leoni, Henryk Birecki, Omer Gila, and Mark J. Kushner
Partial Abstract: In this paper, results from a two-dimensional computer simulation of current extraction from mDBD's sustained in atmospheric pressure N2 will be discussed. The mDBD's are sandwich structures with an opening of tens-of-microns excited with rf voltage waveforms of up to 25 MHz.
Ultrafast laser-induced premelting and structural transformation of gold nanorod
Yong Gan and Shan Jiang
Partial Abstract: Femtosecond laser irradiation of a gold nanorod has been simulated by a method that couples two-temperature model into molecular dynamics. Numerical results show that the surface premelting occurs prior to the initiation of planar defect and propagates from the surface layer into the inside of nanorod.