The syntheses and magnetic properties are reported for three Mn4 single-molecule magnets (SMMs): [Mn4(hmp)6(NO3)2(MeCN)2](ClO4)2·2MeCN (3), [Mn4(hmp)6(NO3)4]·(MeCN) (4), and [Mn4(hmp)4(acac)2(MeO)2](ClO4)2·2MeOH (5). In each complex there is a planar diamond core of MnIII 2MnII 2 ions. An analysis of the variable-temperature and variable-field magnetization data indicate that all three molecules have intramolecular ferromagnetic coupling and a S=9 ground state. The presence of a frequency-dependent alternating current susceptibility signal indicates a significant energy barrier between the spin-up and spin-down states for each of these three MnIII 2MnII 2 complexes. The fact that these complexes are SMMs has been confirmed by the observation of hysteresis in the plot of magnetization versus magnetic field measured for single crystals of complexes 3 and 4. The hysteresis loops for both of these complexes exhibit steps characteristic of quantum tunneling of magnetization. Complex 4 shows its first step at zero field, whereas the first step for complex 3 is shifted to −0.10 T. This shift is attributable to weak intermolecular antiferromagnetic exchange interactions present for complex 3. 相似文献
The principal component analysis (PCA) is used to analyze the high dimensional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components (PCs), which have larger contribution ratios, are chosen as the tabulated scalars to build the look-up chemistry table. Prior tests show that the strained premixed flame structure can be well reconstructed. To highlight the physical meanings of the tabulated scalars in the stratified flames, a modified PCA method is developed, where the mixture fraction is used to replace one of the PCs with the highest correlation coefficient with a mixture fraction. The other two tabulated scalars are then modified with the Schmidt orthogonalization. The modified tabulated scalars not only have clear physical meanings, but also contain passive scalars. The PCA method has good commonality, and can be extended for building the thermo-chemistry table including strain rate effects when different fuels are used. 相似文献
Painleve property and infinite symmetries of the (2+1)-dimensional higher-order Broer-Kaup (HBK) system are studied in this paper. Using the modified direct method, we derive the theorem of general symmetry gro.ups to (2+1)-dimensional HBK system. Based on our theorem, some new forms of solutions are obtained. We also find infinite number of conservation laws of the (2+1)-dimensional HBK system. 相似文献
Painlevé property of the
(2+1)-dimensional multi-component Broer-Kaup (BK) system is considered by using the standard Weiss-Kruskal approaches. Applying the Clarkson and Kruskal (CK) direct method to the (2+1)-dimensional
multi-component BK system, some types of similarity reductions are
obtained. By solving the reductions, one can get the solutions
of the (2+1)-dimensional multi-component BK system. 相似文献
By means of the generalized direct method, a relationship is
constructed between the new solutions and the old ones of the
(3+1)-dimensional breaking soliton equation. Based on the
relationship, a new solution is obtained by using a given
solution of the equation. The symmetry is also obtained for the
(3+1)-dimensional breaking soliton equation. By using the equivalent
vector of the symmetry, we construct a seven-dimensional symmetry
algebra and get the optimal system of group-invariant solutions. To
every case of the optimal system, the (3+1)-dimensional breaking
soliton equation is reduced and some solutions to the reduced
equations are obtained. Furthermore, some new explicit solutions are
found for the (3+1)-dimensional breaking soliton equation. 相似文献
Three classes of quantum states are induced from coherent state (CS) based on three operations associated with the photon creation operator. One class is the famous photon-added coherent state (PACS) introduced by Agarwal and Tara (Phys. Rev. A 43, 492–497, 1991). The other two classes are the orthogonal states of the CS (Here we abbreviate them as OCS1 and OCS2). Indeed, the OCS1 is just the displacement Fock state, and the OCS2 is constructed by orthogonalizer proposed by Kim group (Phys. Rev. Lett. 116, 110501, 2016). In contrast to the original CS, the three induced states can exhibit their respective nonclassical properties. We study and compare some properties for these four quantum states (CS, PACS, OCS1, OCS2). The studied properties include the mean number of photons, the sub-Poissonian character, the squeezing effect in the field quadrature, and the quasi-probability distributions including the Husimi Q function and the Wigner function. Besides, their fidelities between each two of them are also discussed.
Using density functional theory we show that both magnetic and transport properties become chirality-dependent once a nitrogen atom is substituted by an oxygen atom in boron-nitride nanotubes (BNNTs). As chirality increases, the dispersion width of the doping induced impurity state decreases continuously, and this yields progressively larger exchange field and stronger spin polarization. Stronger chirality favors a larger magnetic moment and band insulator while weaker chirality favors a non-magnetic metallic state. In the case of oxygen substitution for a boron atom, the deep in-gap states always yield fully spin-polarized flat-bands and saturated magnetic moment of per oxygen atom. 相似文献