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Artificial heterostructures are typically created by layering distinct materials, thereby giving rise to unique characteristics different from their individual components. Herein, two-dimensional α-MnSe nanosheets with a non-layered structure were fabricated on Ga[sub.0.6]Fe[sub.1.4]O[sub.3] (GFO) films. The superior crystalline properties of MnSe/GFO heterostructures were confirmed through structural and morphological analyses. The remanent polarization is around 1.5 μC/cm[sup.2] and the leakage current density can reach 2 × 10[sup.−3] A/cm[sup.2] under 4 V. In addition, the piezo-response force microscopy amplitude and phase images further supported the ferroelectric property. The significant improvement of coercive field and saturated magnetization, along with the antiparallel signals of Mn and Fe ions observed through synchrotron X-ray analyses, suggest the presence of magnetic interaction within the MnSe/GFO heterostructure. Finally, the excellent photodetector with a photo detectivity of 6.3 × 10[sup.8] Jones and a photoresponsivity of 2.8 × 10[sup.−3] A·W[sup.−1] was obtained under 532 nm in the MnSe/GFO heterostructure. The characteristics of this heterostructure, which include multiferroic, magnetic exchange bias effect, and photodetection capabilities, are highly beneficial for multifunctional devices.

A detailed investigation of contributions to the magnetization of nonmagnetic YB.sub.6, LaB.sub.6, and YbB.sub.6 hexaboride single crystals has been performed, and a procedure for their separation has been proposed. It has been shown that a low value of electronic susceptibility [chi].sub.e(T) in YB.sub.6 and LaB.sub.6 hexaborides seems to be associated with a small effective mass of band carriers, m* ~ 0.5m.sub.0. As a result of this, the Pauli component and Landau diamagnetism cancel each other. It has been found that [chi].sub.e(T) varies in the intervals T < T* (T* ~ 50 K) and T > 150 K, which are attributed to an order-disorder transition below T* and a carriers-related contribution due to the Jahn-Teller structural instability of the boron frame work.

A very fundamental property of both weakly and strongly interacting materials is the nature of their magnetic response. In this work, we detail the growth of crystals of the quasicrystal approximant Fe[sub.4]Al[sub.13] with an Al flux solvent method. We characterize our samples using electrical transport and heat capacity, yielding results consistent with a simple non-magnetic metal. However, magnetization measurements portray an extremely unusual response for a dilute paramagnet and do not exhibit the characteristic Curie behavior expected for a weakly interacting material at high temperature. Electronic structure calculations confirm metallic behavior but also indicate that each isolated band near the Fermi energy hosts non-trivial topologies, including strong, weak, and nodal components, with resultant topological surface states distinguishable from bulk states on the (001) surface. With half-filled flat bands apparent in the calculation, but an absence of long-range magnetic order, the unusual quasi-paramagnetic response suggests the dilute paramagnetic behavior in this quasicrystal approximant is surprising and may serve as a test of the fundamental assumptions that are taken for granted for the magnetic response of weakly interacting systems.

Enhancement in the efficiency of a TiO[sub.2] dye-sensitized solar cell (DSSC) has been demonstrated by introducing ferromagnetic perovskite BiFeO[sub.3] and controlling the magnetic field, which induces two-dimensional material-like properties in the bulk of the TiO[sub.2]-BiFeO[sub.3] DSSC (a 3-dimensional material). The effect of the concentration of BiFeO[sub.3] as well as the magnetization direction on the performance of the TiO[sub.2]-BiFeO[sub.3] DSSC has been investigated. After magnetization, it was confirmed that the current density, efficiency, and open circuit voltage of the TiO[sub.2]-BiFeO[sub.3] DSSC were increased. The observed phenomena have been explained in terms of the Hall effect which is responsible for the reduction of the degree of freedom of the electron movement resulting in the two-dimensional material-like properties in the bulk of the TiO[sub.2]-BiFeO[sub.3] DSSC.

Ba[sub.1−x]Sr[sub.x]Fe[sub.12]O[sub.19] (x = 0.0, 0.5 and 1.0) hard-magnetic nanohexaferrites prepared by autocombustion were primarily investigated using Mössbauer spectroscopy and optical studies. Morphological examination by electron scanning microscopy revealed that the particles agglomerated into grains with a hexagonal shape. The grain size increases with the amount of Sr content, from ca. 490 nm (x = 0.0) to ca. 700 nm (x = 1.0). Room-temperature Mössbauer spectroscopy showed that the mean hyperfine field increased with the substitution of Ba[sup.2+] by Sr[sup.2+], consistent with magnetization results. The preferential sites occupied by Fe ions in the hexaferrite structure were determined. Optical studies revealed that all compounds absorb up to ca. 1000 nm, and that the bandgap energy decreases with increasing Sr content.

Bi.sub.1-xEr.sub.xFeO.sub.3 (BE.sub.xFO, x = 0.07-0.12) films have been deposited on fluorine-doped SnO.sub.2 (FTO) substrates by a chemical solution deposition method (CSD). The structure and multiferroic properties were investigated. The results indicate that there is a structural transition from the typical rhombohedral-R3c:H (BiFeO.sub.3) to two-phase coexistence of rhombohedral-R3c:H and rhombohedral-R3m:R (BE.sub.xFO). The abundant Fe.sup.2+ are observed in BE.sub.xFO, which induces the larger leakage current. The BE.sub.0.09FO shows the ferroelectric switching current of 1.42 x 10.sup.-2 A and the enhanced magnetization (saturation magnetization M.sub.s ~ 2.60 emu/cm.sup.3). From the investigation, the BE.sub.xFO films will be expected to show the great multiferroic properties after reducing the leakage current.

Background & Purpose: APT-CEST imaging allows for assessing tumor infiltration, providing information on protein concentrations and intracellular pH changes (1). The method acquires a Z-spectrum. This can be time-consuming, especially for a large number of frequency offsets and full tumor coverage. Here, we present a fast multi-slice CEST-EPI sequence, extending the work by Sun et al. (2) via further optimizing the saturation scheme. Methods: The proposed sequence employs a pre-saturation CEST pulse train, driving the magnetization into a steady-state, followed by a secondary module comprising one CEST pulse and an EPI acquisition, being embedded in a slice and a frequency offset loop. This maintains the steady-state throughout the whole measurement, being faster than the standard scheme which employs pre-saturation for each single frequency offset. Up to 16 slices per volume can be acquired in 8 s (80 mm coverage, in-plane resolution: 3 x 3 [mm.sup.2]). The sequence was tested with a maximum increment of 0.5 ppm. Both schemes were compared in-vitro on a phantom with different T1 times and in-vivo. Result: In-vitro, no significant difference was found via MTRa-sym(3.5 ppm) (Fig. 1). The comparison in-vivo over 16 slices shows a similar contrast for the white matter as well as for the tumor. Only CSF has a higher signal compared to the proposed sequence (Fig. 2). Conclusion: The proposed sequence yields a speedup by a factor of two via restriction to a single pre-saturation module. Comparison with the results of the standard scheme revealed no significant differences.

The relaxation of nuclear magnetization in the .sup.29Si:B crystals obeys power-law kinetics at 300 K due to direct electron-nuclear relaxation. Admixture of the exponential relaxation associated with spin diffusion was revealed at higher temperatures. The inhomogeneous distribution of linear deformation defects was revealed by electron paramagnetic resonance. This factor mainly contributes to power-law kinetics of nuclear spin relaxation.

Neutron powder diffraction and inelastic neutron scattering data were used to simulate and understand the magnetization and heat capacity curves of the pseudobinary [Tb.sub.x][Pr.sub.1-x][Al.sub.2], with x = 0.10 and 0.25, as a function of temperature. From the Rietveld analysis, we concluded that no crystallographic transition occurs in these samples, and the high symmetry of the magnetic structure was confirmed. Moreover, the different contributions from the reflection planes could be related to the known exchange bias-like effect characteristic for the x = 0.25 sample, also suggesting the existence of some rearrangement of the magnetic moments or even the presence of spin frustration in this system. Finally, the obtained set of theoretical parameters using the mean field approach for the two systems consisting of two sublattices allowed the experimental data to be described and to explain their physical behaviors. The ensemble of our results leads us to affirm that the quadrupolar interactions as well as an existence of some rearrangement of the magnetic moments or a frustration play an important role in the strong unidirectional anisotropy and the exchange bias-like effect observed in this pseudobinary system.

Hintergrund: Early predictors of successful nerve regeneration are urgently needed to avoid a waste of time and thus functional outcome following severe nerve injury. Up to date, however, clinical decision making mainly relies on a watch-and-wait strategy to identify potential candidates for surgical intervention in the case of failing re-innervation [1]. We used a ultra high field magnetic resonance neurography (MRN) approach in a rodent model of peripheral nerve injury to identify early MR-parameters within the nerve which may be used to predict functional outcome. Methoden: 12 female S.-Dawley rats underwent transection of the right Median nerve at upper arm level. In the gold standard group (n = 6, \"Gold\"), an autograft of reversed Median nerve (1 cm) was re-implanted while in the negative control group (n = 6, \"Neg\"), a 1 cm nerve gap was left in place. These two groups were imaged four times at forearm level on a 9.4 T MR-scanner 3, 10, 30 and 90 d post surgery. The protocol comprised a set of T2-w RARE, T1-w FLASH ([+ or -] MT-pulse), DTI and MSME sequences. Groups were followed behaviourally and histological parameters were obtained after sacrifice. Results were compared longitudinally and between groups. Ergebnisse: At 30 d, significant differences between Gold and Neg are noted for the magnetization transfer ratio (MTR), apparent diffusion coefficient (ADC) and radial diffusivity (RD) while other parameters show similar pathological alterations, namely T2-Time, proton density, fractional anisotropy and cross sectional area (CSA). At that time, only first signs of clinical recovery (~10% of the grip strength plateau) are present in the Gold while no function is seen in the Neg. The first time points do not show such group differences and at the last time point, only a larger CSA within the Gold is of note. Substantial phenotypical differences persist with the Neg only regaining ~20% grip strength of the Gold and showing a markedly reduced axon density. Fazit: Using ultra high field MRN in a rigorous preclinical in vivo model we identify MTR, ADC and RD as early in vivo parameters of the regenerating nerve which may potentially be used in a translational setting to predict functional outcome and guide therapeutic decision making in the future.