Abstract
The discovery of two-dimensional magnets has initiated a new field of research, exploring both fundamental low-dimensional magnetism, and prospective spintronic applications. Recently, ...observations of magnetic skyrmions in the 2D ferromagnet Fe
3
GeTe
2
(FGT) have been reported, introducing further application possibilities. However, controlling the exhibited magnetic state requires systematic knowledge of the history-dependence of the spin textures, which remains largely unexplored in 2D magnets. In this work, we utilise real-space imaging, and complementary simulations, to determine and explain the thickness-dependent magnetic phase diagrams of an exfoliated FGT flake, revealing a complex, history-dependent emergence of the uniformly magnetised, stripe domain and skyrmion states. The results show that the interplay of the dominant dipolar interaction and strongly temperature dependent out-of-plane anisotropy energy terms enables the selective stabilisation of all three states at zero field, and at a single temperature, while the Dzyaloshinksii-Moriya interaction must be present to realise the observed Néel-type domain walls. The findings open perspectives for 2D devices incorporating topological spin textures.
The texture in an extruded cordierite honeycomb an d its effects on mechanical properties were To understand the behaviour of the extruded the elas tic properties of a natural cordierite crystal with ...a transversal isotropic behaviour determined by differen t methods. The CTE and modulus in an extruded struct ure were correlated with the preferred orientati on of the and single crystal measurements. The correl ated were compared with the measured properties. The modulus showed a similar behaviour in different while the CTE showed a strong anisotropy, and it thought that microcracking may influence both .
New copolymers of styrene with
N-acryloyl
p-nitroaniline or
N-diethyl methylenemalonate
p-nitroaniline chromophores were synthesized and characterized by size exclusion chromatography (SEC), thermal ...analyses (DSC, TGA) and reflectometry. The linear optical properties of the polystyrene copolymers and the polystyrene (PS) doped with
p-nitroaniline derivative chromophores were investigated and were related to the chromophore content in the matrix by prism coupling at 633
nm. Thin films of the polymers with good optical quality were prepared by the spin coating method. The glass transition and decomposition temperatures and the refractive index profile of the copolymers were similar to those of the parent PS. On the other hand, the PS doped with
p-nitroaniline derivative chromophores had lower glass transition temperatures attributed to the plasticizing effect of the chromophore and different refractive index profiles compared with the parent PS.
The discovery of two-dimensional magnets has initiated a new field of research, exploring both fundamental low-dimensional magnetism, and prospective spintronic applications. Recently, observations ...of magnetic skyrmions in the 2D ferromagnet Fe
GeTe
(FGT) have been reported, introducing further application possibilities. However, controlling the exhibited magnetic state requires systematic knowledge of the history-dependence of the spin textures, which remains largely unexplored in 2D magnets. In this work, we utilise real-space imaging, and complementary simulations, to determine and explain the thickness-dependent magnetic phase diagrams of an exfoliated FGT flake, revealing a complex, history-dependent emergence of the uniformly magnetised, stripe domain and skyrmion states. The results show that the interplay of the dominant dipolar interaction and strongly temperature dependent out-of-plane anisotropy energy terms enables the selective stabilisation of all three states at zero field, and at a single temperature, while the Dzyaloshinksii-Moriya interaction must be present to realise the observed Néel-type domain walls. The findings open perspectives for 2D devices incorporating topological spin textures.
We studied MEH-PPV and MEH-PPB which are derivatives of poly(
p-phenylenevinylene) (PPV), synthesized via the so-called HORNER-polycondensation route. The residual sub-bandgap absorptions of MEH-PPV ...were found to be extremely low at
λ⩾1064 nm as compared to other PPVs. We attribute this fact to its very low defect density. MEH-PPV enables the fabrication of slab waveguides with propagation losses which are well below 1 dB/cm at 1064 nm. Comparative studies of the cubic nonlinearity
χ
(3), the photodegradation and the damage thresholds at 1064 nm of PPV, MEH-PPV and MEH-PPB demonstrate that polycondensation-type MEH-PPV has the greatest potential for the realization of nonlinear optical waveguide applications.
A miniature tetrode system, according to F. Burstert, D. Winkler and B. Lischke Microelectron. Eng. 31 (1996) 95, for the generation of a low-voltage electron probe was investigated and further ...developed. The tetrode system consists of a Schottky cathode and a miniaturized lens, composed of three conventional electron microscopical apertures, which are used as electrodes. We tested two configurations with different aperture thicknesses and bore diameters experimentally and also made simulations of these lenses. Two kinds of middle electrodes, a flat and a top-hat aperture, were used. In most cases the experimental data show a good agreement with the theoretically predicted values of the examined tetrode system.
Third-harmonic generation (THG) spectroscopy was performed for oligo(1,4-phenyleneethynylene)s (OPEs) with terminal donor−acceptor (DA) substitution and compared to the results of merely donor ...substituted OPEs and regular OPE chains with 2,5-dipropoxy benzene rings. Both, extension of the conjugation and push−pull effect enhance the molecular hyperpolarizability γ, even for the DAOPEs, which exhibit a hypsochromic shift of the long-wavelength absorption for increasing length L of the conjugated chain.
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