crystallographic direction
Recently Published Documents

AbstractUnidirectional Spin Hall magnetoresistance (USMR) is a non-linear phenomenon recently observed in ferromagnet (FM)/nonmagnetic metal (NM) bilayer structures. Two very different mechanisms of USMR have been proposed; one relies on the current-direction-dependence of electron-magnon scattering in a FM layer, and the other on the current-direction-dependence of the spin accumulation at the FM/NM interface. In this study, we investigate the USMR in epitaxial Cr/Fe bilayers finding that the USMR is significantly enhanced when the Fe magnetization is aligned to a particular crystallographic direction where the magnon magnetoresistance (MMR) by the electron-magnon scattering becomes stronger. This highlights the importance of the electron-magnon scattering for the understanding of USMR in Cr/Fe bilayers. Our result also suggests a route to enhance the efficiency of magnon generation in the magnonic devices. Lastly, we discuss the Ising-type spin exchange as a possible origin of the crystallographic direction dependences of the USMR and the MMR.

Abstract The results of the samples study of the magnetostrictive-piezo-conductive structure based on Metglas/GaAs/Metglas with different geometric dimensions are presented in this article. The sizes of the studied samples were 10.2x5 2x0.63 mm; 15.2x5.1x0 63 mm; 20.1x5. 2x0.63 mm - with epitaxial layers on a gallium arsenide (GaAs) plate and 15.2x5.1x0.62 mm - without epitaxial layers. The obtained results confirm the initial theoretical calculations of the observation of the maximum magnetoelectric effect in the plane of the GaAs (100) plate with the orientation of the long side of the sample along the crystallographic direction [011]. The maximum αME was observed in a sample with dimensions of 15.2x5.1x0.62 mm without epitaxial layers and was equal to αME = 54.19 V/(cm·Oe) at the resonance frequency RF = 145.8 kHz. In conclusion, the prospects for practical application of a design based on the Metglas/GaAs/Metglas magnetostrictive-piezo-semiconductive structure as a magnetoelectric resistor, a magnetoelectric diode and a magnetoelectric transistor are given.

Among processes involving plastic deformation, sheet metal forming requires a most accurate description of plastic anisotropy. One of the main sources of mechanical anisotropy is the intrinsic anisotropy of the constituent crystals. In this paper, we present the single-crystal yield criterion recently developed by Cazacu et al. [1] and its application to the prediction of anisotropy in uniaxial tension of strongly textured polycrystalline sheets. Namely, it is shown that using this single crystal yield criterion the Lankford coefficients exist and have finite values for all loading orientations. Moreover, the variation of both the yield stress and Lankford coefficients with the crystallographic direction can be expressed analytically. An application of this criterion to forming a cylindrical cup from a single crystal of (100) orientation is presented. Finally, we show that using this single-crystal model, one can describe well the effect of the spread around an ideal texture component on the anisotropy in uniaxial tensile properties of a polycrystal.

Changes in the elastic constants cij of disordered cubic titanium carbide TiCy with an increasing the defectiveness of the carbon sublattice are estimated for the first time. It was found that the deviation of titanium carbide from the stoichiometric composition TiC1.0 leads to a decrease in the elastic stiffness constants cij of disordered TiCy carbide with a simultaneous increase in elastic anisotropy. The distributions of Young's modulus E and Poisson's ratio μ in the (100) plane and the distributions of the shear modulus G in the (100), (110), and (111) planes have been calculated as functions on the crystallographic direction [hkl] and on the relative carbon content y in TiCy carbide. The lowest values of the shear modulus Ghkl for TiCy are observed in the (111) plane.

The results of measurements of the dielectric parameters of TeO2 samples in the microwave range are presented. The measurements were carried out in X-band by the cavity perturbation method using a measuring setup based on a biconical resonator. The advantages of using a high-Q biconical resonator for measuring the dielectric parameters of a paratellurite sample are considered. The determination of the dielectric parameters of the samples is based on finite element computational model and using digital method for determining the natural frequency by fractional rational approximation of the frequency response. The influence of the deviation of the sample shape from the cylindrical on the resonator parameters and the measurement error is considered. The estimate of the dielectric constant of TeO2 in the crystallographic direction [110] was 24.4, the dielectric loss factor such as tanδ is estimated as 3·10-4. The results obtained are in good agreement with the reference results presented in the scientific literature.

AbstractHighly confined and low-loss polaritons are known to propagate isotropically over graphene and hexagonal boron nitride in the plane, leaving limited degrees of freedom in manipulating light at the nanoscale. The emerging family of biaxial van der Waals materials, such as α-MoO3 and V2O5, support exotic polariton propagation, as their auxiliary optical axis is in the plane. Here, exploiting this strong in-plane anisotropy, we report edge-tailored hyperbolic polaritons in patterned α-MoO3 nanocavities via real-space nanoimaging. We find that the angle between the edge orientation and the crystallographic direction significantly affects the optical response, and can serve as a key tuning parameter in tailoring the polaritonic patterns. By shaping α-MoO3 nanocavities with different geometries, we observe edge-oriented and steerable hyperbolic polaritons as well as forbidden zones where the polaritons detour. The lifetime and figure of merit of the hyperbolic polaritons can be regulated by the edge aspect ratio of nanocavity.

When performing transmission polychromatic beam topography, the extensions to the line segments of the diffraction images of a straight dislocation are shown to intersect at a single point on the X-ray film. The location of this point, together with the diffraction pattern recorded on the film by synchrotron radiation, gives the crystallographic direction [hkl] of the dislocation unambiguously. The results of two synchrotron topography experiments are presented. Very long dislocations found in the center of a large 450 mm-diameter Czochralski silicon crystal align with the growth direction [001]. In the other silicon sample, the dislocations are of mixed type and along the [011] direction.