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21.
The dynamics of entanglement for two-mode magnons in an antiferromagnet is investigated according to the entanglement criterion proposed by Duan et al. [L.M. Duan, G. Giedke, J.I. Cirac, P. Zoller, Phys. Rev. Lett. 84 (2000) 2722]. It is shown that entanglement between the two modes of magnons can be generated and occurs periodically with time. 相似文献
22.
A. El-Korashy 《Solid State Communications》2005,135(5):298-303
Single crystals [N(CH3)4]2MnCl4 and [N(CH3)4]2CoCl4 were grown by the slow evaporation technique from the super-saturated solutions. The samples obtained were undergone the X-ray and spectroscopic studies. Absorption spectra in the paraelectric phase at T=303 K have been recorded using the Shimadzu 160A double beam automatic scanning spectrophotometers. On the basis of the exchange charge model and Racah theory the crystal field parameters and Racah parameters have been calculated; all absorption bands for both crystals were given an assignment. 相似文献
23.
M. Fiebig D. Fröhlich S. Leute R.V. Pisarev 《Applied physics. B, Lasers and optics》1998,66(3):265-270
2 O3, in which the time-invariant second-harmonic reference can be generated either intrinsically by the crystal or externally
by use of the new technique, so that both methods may be compared. The technique is then used to visualize the domain structure
of YMnO3, an antiferromagnetic crystal which does not provide the time-invariant reference wave intrinsically. The experiments demonstrate
the wide applicability of the method.
Received: 13 June 1997 相似文献
24.
Oscillatory Activities in Regulatory Biological Networks and Hopf Bifurcation 总被引:1,自引:0,他引:1 下载免费PDF全文
Exploiting the nonlinear dynamics in the negative feedback loop, we propose a statistical signal-response model to describe the different oscillatory behaviour in a biological network motif. By choosing the delay as a bifurcation parameter, we discuss the existence of Hopf bifurcation and the stability of the periodic solutions of model equations with the centre manifold theorem and the normal form theory. It is shown that a periodic solution is born in a Hopf bifurcation beyond a critical time delay, and thus the bifurcation phenomenon may be important to elucidate the mechanism of oscillatory activities in regulatory biological networks. 相似文献
25.
We have carried out accurate generalized-gradient-corrected fully-relativistic full-potential calculations for Sr1−xCaxRuO3 (x=0, 0.25, 0.5, 0.75, and 1) in para-, ferro-, and A-, C-, and G-type antiferromagnetic configurations. We have performed electronic structure calculations for the experimentally observed orthorhombic structure as well as the hypothetical cubic structure. Our results are analyzed with the help of total, site-, spin-, and orbital-projected density of states. The total-energy studies show that CaRuO3 stabilizes in the G-type antiferromagnetic state. The octahedral tilting owing to the relatively small radius of Ca2+ leads to weak hybridization between Ru 4d and O 2p. This weak hybridization along with exchange splitting causes a pseudogap-like feature close to the Fermi level, which should stabilize G-type antiferromagnetic ordering in CaRuO3. However, powder neutron diffraction data on CaRuO3 taken at 8 and do not show any magnetic peaks, implying that CaRuO3 exhibits a spin-glass-like state with dominant short-range antiferromagnetic interaction. The calculated magnetic ground state of Sr1−xCaxRuO3 is found to be consistent with the experimental findings. We have also calculated optical spectra as well as X-ray and ultra-violet photoemission spectra and Ru and O K-edge X-ray absorption spectra for G-type CaRuO3 and found good agreement with available experimental spectra. 相似文献
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27.
The magnetoelectric properties of a rhombohedrally distorted perovskite BiFe0.7Mn0.3O3 are reported. An anomaly in the dielectric constant, related to enhanced thermal fluctuations around the antiferromagnetic transition, was induced near room temperature by the substitution of Mn for Fe in BiFeO3. This substitution also brings about non-trivial magnetocapacitance effects at room temperature. 相似文献
28.
Protocatechualdehyde (PCA) is one of the effective ingredients extracted from Danshen (Radix Salviae Miltiorrhizae) and was employed to modify the silk fibroin (SF) by graft polymerization and surface adsorption. The surface composition of modified SF was characterized by attenuated total reflectance Fourier-transform infrared (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and UV spectrophotometer. The anticoagulant activity of modified SF was assessed by in vitro coagulation test and platelet adhesion measurement. The endothelial cell affinity was evaluated by a parallel plate flow chamber. The test results indicated that with the introduction of PCA into SF, the anticoagulant activity has been improved obviously. And the SF surface composition altered by PCA, but did not disturb its β-sheet conformation. Moreover, the adsorbed PCA on SF surface can enhance the endothelial cell affinity. 相似文献
29.
Z.M. Tian J.H. He Y.Q. Wang P. Li H.Y. Xie L. Liu S.Y. Yin 《Solid State Communications》2007,142(9):545-549
Magnetic properties have been investigated on Mn doped TiO2(Ti0.98Mn0.02O2) bulk samples prepared by solid state reaction, which were sintered at different temperature ranging from 450 °C to 900 °C in air and argon atmosphere, respectively. The results show that the magnetic properties were strongly dependent on the sintering temperature and atmosphere. For samples sintered in air, the magnetization initially increase with the increase of sintering temperature up to 600 °C and thereafter it decrease. While the magnetization of samples sintered in argon atmosphere decreases monotonically with the increase of sintering temperature. Furthermore, for samples sintered at 600 °C in air, the magnetic susceptibility exhibits a dominant Curie-Weiss behaviour and no magnetic transition is observed over the temperature range from 10 to 300 K. In contrast, for samples sintered in argon atmosphere, besides the magnetic transition near 45 K perhaps caused by Mn3O4, another magnetic transition appears near room temperature. 相似文献
30.
With employing the Dyson-Maleev transformation and the coherent-state ansatz, two partial different motion equations are obtained from Hamiltonian of antiferromagnet CsFeBr3. By using the method of multiple scales and the long-wavelength approximation, these equations are changed into a nonlinear Schrödinger equation. By applying inverse-scattering transformation, solution of the equation is obtained, solitary excitations in antiferromagnet CsFeBr3 are also investigated. 相似文献