Search results for "Zoe"

Electric-Field Control of Spin-Orbit Torques in Perpendicularly Magnetized W/CoFeB/MgO Films

2020

Controlling magnetism by electric fields offers a highly attractive perspective for designing future generations of energy-efficient information technologies. Here, we demonstrate that the magnitude of current-induced spin-orbit torques in thin perpendicularly magnetized CoFeB films can be tuned and even increased by electric-field generated piezoelectric strain. Using theoretical calculations, we uncover that the subtle interplay of spin-orbit coupling, crystal symmetry, and orbital polarization is at the core of the observed strain dependence of spin-orbit torques. Our results open a path to integrating two energy efficient spin manipulation approaches, the electric-field-induced strain a…

Interface-induced enhancement of piezoelectricity in the (SrTiO 3 ) m /(BaTiO 3 ) M−m superlattice for energy harvesting applications

2019

This research is funded by the Latvian Council of Science, project No. lzp-2018/1-0147. The computer resources were provided by Stuttgart Supercomputing Center (project DEFTD 12939) and Latvian Super Cluster (LASC). Many thanks to R. Dovesi, A. Erba, and M. Rérat for numerous stimulating discussions.

Direct observation of polar nanostructures in PLZT ceramics for electrooptic applications

2004

ABSTRACTTransparent Pb1-yLay(Zr1-xTix)1-y/4O3(PLZT, y=0.0975, x=0.35) ceramics prepared via hot pressing techniques were studied via piezoelectric force microscopy (PFM). Clear piezoelectric contrast is observed in a cubic relaxor phase indicating spatial distribution of polarization with an average cluster size of about 50 nm. The irregular polarization pattern is associated with the formation of a glassy state, where random electric and stress fields are responsible for the disruption of the long-range ferroelectric order. Local poling of the ceramics resulted in the formation of a stable micron-size domain that could be continuously switched under varying dc bias (local hysteresis loop).…

SYNTHESIS AND CHARACTERIZATION OF SB-SUBSTITUTED (K0.5Na0.5)NbO3 PIEZOELECTRIC CERAMICS

2008

ABSTRACT Lead-free piezoelectric ceramics (K0.5Na0.5)(Nb1-xSbx)O3+0.5 mol.%MnO2, where x = 0 ÷ 0.10, with single phase structure and rhombohedral symmetry at room temperature were prepared by conventional ceramic technology. The optimal sintering temperatures of compositions were within 1100°–1140°C. MnO2 functions as a sintering aid and effectively improves the densification. The samples reached density from 4.26 g/cm3 for undoped (K0.5Na0.5)NbO3 to 4.40 g/cm3 for Mn/Sb5+ co-doped ceramics. The co-effects of MnO2 doping and Sb5+ substitution lead to significant improvement in dielectric and piezoelectric properties: e at the Tc increased from 6000 (KNN) to 12400 (x = 0.04), d33 = 92 ÷ 192 …

SINTERING OF LEAD-FREE (K0.5Na0.5)NbO3 BASED SOLID SOLUTION

2009

ABSTRACT In this study lead-free solid solution (K0.5Na0.5)NbO3 was prepared, structure, dielectric parameters of ceramics were investigated. The doping of sintering aids did not affect the crystallographic structure of the ceramics significantly; all ceramic samples had a single-phase perovskite structure. Added elements CdO, ZnO, MnO2, V2O5 effectively decreased the sintering temperature of KNN by 50°–80°C. All sintering aids influenced sinterability, microstructure and dielectric properties of ceramics. Dielectric constant for doped samples increased from 6000 up to 8000; Pr = 15 μC/cm2, Ec = 9 kV/cm, d33 = 110 pC/N, kp = 0.38 and Qm = 190 for MnO2 doped samples.

Active shape correction of a thin glass/plastic x-ray mirror

2015

Optics for future X-ray telescopes will be characterized by very large aperture and focal length, and will be made of lightweight materials like glass or plastic in order to keep the total mass within acceptable limits. Optics based on thin slumped glass foils are currently in use in the NuSTAR telescope and are being developed at various institutes like INAF/OAB, aiming at improving the angular resolution to a few arcsec HEW. Another possibility would be the use of thin plastic foils, being developed at SAO and the Palermo University. Even if relevant progresses in the achieved angular resolution were recently made, a viable possibility to further improve the mirror figure would be the app…

Solution-processible electrode materials for a heat-sensitive piezoelectric thin-film sensor

2012

Abstract Piezoelectric sensors are needed in a wide range of applications from physiological measurement applications to industrial monitoring systems. Custom-designed, highly integratable and cost-effective sensor elements can be manufactured by using flexible materials in combination with high-throughput printing for fabrication. This would also enable the embedding of ubiquitous sensors in our living environment to improve the common welfare. Here, we have fabricated flexible piezoelectric sensor elements using printing methods. We demonstrated that alternative, printable electrode materials are compatible with temperature-sensitive functional substrates. Low-temperature curable electrod…

Dipoles in 4,12,4-graphyne

2021

Abstract In present work, B-N pairs as dipole source were introduced into 4,12,4-graphyne. According to the density functional theory (DFT) simulations, the electronic configurations of the doped 4,12,4-graphyne systems were significantly modified owing to the built-in electric fields caused by the B-N dipoles. Different B-N concentrations and arrangements can alter the electronic structure of 4,12,4-graphyne. Consequently, an obvious in-plane piezoelectricity can also be induced. Moreover, the direct band gap can be delicately modulated from 150 meV to 660 meV at PBE level. The B-N dipoles can also greatly enhance the light absorption instead of shifting the absorption region. According to…

High Electromechanical Coupling in Relaxor Pb(Sc<sub>1/2</sub>Nb<sub>1/2</sub>) O<sub>3</sub> - PbTiO<sub>3…

1997

Magneto-Electro-Elastic Bimorph Analysis by the Boundary Element Method

2008

The influence of the magnetic configuration on the behavior of magneto-electro-elastic bimorph beams is analyzed by using a boundary element approach. The problem is formulated by using the generalized displacements and generalized tractions. The boundary integral equation formulation is obtained by extending the reciprocity theorem to magneto-electro-elastic problems; it is numerically implemented by using the boundary element method multidomain technique to address problems involving nonhomogeneous configurations. Results under different magnetic configurations are compared highlighting the characteristic features of magnetopiezoelectric behavior particularly focusing on the link between …