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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 5994-5996 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Because the light rare-earth element Nd makes a significant contribution to the Kerr effect and the heavy rare-earth element Dy can improve the coercivity and perpendicular anisotropy, NdDyFeCoTi magneto-optical material was studied. The alloy targets were prepared by a vacuumm melting method with compositions (NdxDy1−x)25(Fe0.65Co0.30Ti0.05)75 with x=0.2–0.3. Because of the addition of Ti, the mechanical strength of the target was improved. Amorphous NdDyFeCoTi films were prepared by rf magnetron sputtering onto glass substrates at zero bias, a low Ar pressure of 3–7 mTorr, and a low-input sputtering power of 100–300 W. The magnetic and magneto-optical properties of these films were studied by VSM, Kerr hysteresis tracer, and Auger electron spectroscopy. The Kerr angle θk of 0.3° and the coercive force Hc of 3–5 kOe have been found. The stability of the films was examined by exposure in air for one month and annealing at 100–250 °C. The magneto-optical properties of the films exhibit no obvious change after exposure in air, but after annealing at 200–250 °C the properties of NdDyFeCoTi with a SiO2 protective layer became poor. As a result, it is necessary to improve the stability of NdDyFeCoTi magneto-optical films by a protective layer without oxygen such as AlN.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2015-08-05
    Description: We presented a quantitative study on the Fe-doping concentration dependence of optical nonlinearities and ultrafast carrier dynamics in Fe-doped GaN (GaN:Fe) single crystals using picosecond Z-scan and femtosecond pump-probe with phase object techniques under two-photon excitation. In contrast to the two-photon absorption that was found to be independent on the Fe-doping, the nonlinear refraction decreased with the Fe concentration due to the fast carrier trapping effect of Fe 3+ /Fe 2+ deep acceptors, which simultaneously acted as an efficient non-radiative recombination channels for excess carriers. Remarkably, compared to that of Si-doped GaN bulk crystal, the free-carrier refraction effect in GaN:Fe crystals was found to be enhanced considerably since Fe-doping and the effective carrier lifetime (∼10 ps) could be tuned over three orders of magnitude at high Fe-doping level of 1 × 10 19  cm −3 .
    Print ISSN: 0003-6951
    Electronic ISSN: 1077-3118
    Topics: Physics
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  • 3
    Publication Date: 2015-05-01
    Description: The temperature-dependent diffusion coefficient of interstitial helium in zirconium carbide (ZrC) matrix is calculated based on the transition state theory. The microscopic parameters in the activation energy and prefactor are obtained from first-principles total energy and phonon frequency calculations including the all atoms. The obtained activation energy is 0.78 eV, consistent with experimental value. Besides, we evaluated the influence of C and Zr vacancies as the perturbation on helium diffusion, and found the C vacancy seems to confine the mobility of helium and the Zr vacancy promotes helium diffusion in some extent. These results provide a good reference to understand the behavior of helium in ZrC matrix.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 4
    Publication Date: 2014-11-05
    Description: Perovskite phase SnTiO 3 was predicted to have a large spontaneous polarization of 1.1 C/m 2 , but its synthesis has been unsuccessful so far. Here, we calculated the ferroelectric properties of a series of Ruddleson-Popper (RP) phase SnO(SnTiO 3 ) n ( n  = 1 ∼ 6), with perovskite SnTiO 3 as the ending structure ( n  = ∞), using the first principles calculations. An analysis of RP phase tolerance factor indicated that the fabrication of the RP phase SnO(SnTiO 3 ) n may be easier than that for SnTiO 3 . For bulk SnO(SnTiO 3 ) 1 , the most stable phase is Aba2 with a spontaneous polarization of 0.53 C/m 2 along [110]. Aba2 is also the most stable phase for SnO(SnTiO 3 ) 1 under biaxial strain. For RP phase SnO(SnTiO 3 ) n on a SrTiO 3 substrate, there is also a phase transition with the increasing layer thickness n . The polarization increases with strain or layer thickness. The ferroelectric properties and size effect in the free standing RP phase SnO(SnTiO 3 ) n nanosheets were also investigated, and the in -plane polarization is 60% larger than that of the bulk.
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
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  • 5
    Publication Date: 2016-06-29
    Description: The integrable nonlocal nonlinear Schrödinger equation with the self-induced parity-time-symmetric potential [M. J. Ablowitz and Z. H. Musslimani, Phys. Rev. Lett. 110 , 064105 (2013)] is investigated, which is an integrable extension of the standard nonlinear Schrödinger equation. Its novel higher-order rational solitons are found using the nonlocal version of the generalized perturbation ( 1 , N − 1 ) -fold Darboux transformation. These rational solitons illustrate abundant wave structures for the distinct choices of parameters (e.g., the strong and weak interactions of bright and dark rational solitons). Moreover, we also explore the dynamical behaviors of these higher-order rational solitons with some small noises on the basis of numerical simulations.
    Print ISSN: 1054-1500
    Electronic ISSN: 1089-7682
    Topics: Physics
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  • 6
    Publication Date: 2015-10-14
    Description: In this paper, we study the Klein-Gordon-Zakharov (KGZ) system, which describes the interaction between the Langmuir wave and ion sound wave in a high-frequency plasma. By means of the Hirota method and symbolic computation, bright and mixed-type soliton solutions are obtained. For the one soliton, amplitude of E is positively related to β 2 , and that of n is inversely related to β 2 , while they are both positively related to α , where E refers to the high-frequency part of the electrostatic potential of the electric field raised by the electrons, and n represents the deviation of ion density from its equilibrium, β 2 and α are the plasma frequency and ion sound speed, respectively. Head-on interactions between the two bright solitons and two mixed-type ones are respectively displayed. With β 2 increasing, the head-on interaction is transformed into an overtaking one. Bright bound-state solitons are investigated, and the interaction period decreases with α increasing. Furthermore, with the external forces Γ 1 ( t ) and Γ 2 ( t ) introduced, the perturbed KGZ system is studied numerically for its associated chaotic motions. Both the weak and developed chaotic motions can be observed. Γ 1 ( t ) and Γ 2 ( t ) have different effects on the chaotic motions: the chaotic motion can be weakened by decreasing the amplitude of Γ 1 ( t ) or increasing the amplitude and frequency of Γ 2 ( t ) .
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
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  • 7
    Publication Date: 2015-12-19
    Description: We study higher-order rogue wave (RW) solutions of the coupled integrable dispersive AB system (also called Pedlosky system), which describes the evolution of wave-packets in a marginally stable or unstable baroclinic shear flow in geophysical fluids. We propose its continuous-wave (CW) solutions and existent conditions for their modulation instability to form the rogue waves. A new generalized N -fold Darboux transformation (DT) is proposed in terms of the Taylor series expansion for the spectral parameter in the Darboux matrix and its limit procedure and applied to the CW solutions to generate multi-rogue wave solutions of the coupled AB system, which satisfy the general compatibility condition. The dynamical behaviors of these higher-order rogue wave solutions demonstrate both strong and weak interactions by modulating parameters, in which some weak interactions can generate the abundant triangle, pentagon structures, etc. Particularly, the trajectories of motion of peaks and depressions of profiles of the first-order RWs are explicitly analyzed. The generalized DT method used in this paper can be extended to other nonlinear integrable systems. These results may be useful for understanding the corresponding rogue-wave phenomena in fluid mechanics and related fields.
    Print ISSN: 1054-1500
    Electronic ISSN: 1089-7682
    Topics: Physics
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  • 8
    Publication Date: 2014-10-28
    Description: Both kinetically balanced (KB) and kinetically unbalanced (KU) rotational London orbitals (RLO) are proposed to resolve the slow basis set convergence in relativistic calculations of nuclear spin-rotation (NSR) coupling tensors of molecules containing heavy elements [Y. Xiao and W. Liu, J. Chem. Phys.138, 134104 (2013)]. While they perform rather similarly, the KB-RLO Ansatz is clearly preferred as it ensures the correct nonrelativistic limit even with a finite basis. Moreover, it gives rise to the same “direct relativistic mapping” between nuclear magnetic resonance shielding and NSR coupling tensors as that without using the London orbitals [Y. Xiao, Y. Zhang, and W. Liu, J. Chem. Theory Comput.10, 600 (2014)].
    Print ISSN: 0021-9606
    Electronic ISSN: 1089-7690
    Topics: Chemistry and Pharmacology , Physics
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  • 9
    Publication Date: 2016-05-07
    Description: A model for the nonlinear dust-ion-acoustic waves in a two-ion-temperature, magnetized dusty plasma is studied in this paper. Via the symbolic computation, one-, two- and N -soliton solutions are obtained. It is found that when μ e μ i 〈 2 T i 2 T e 2 + T i T e , the soliton amplitude is positively related to μ e , μ i , T i , Z d , and B 0 , but inversely related to T e and m d , with T e , T i , μ e , and μ i as the temperature of an electron, temperature of a positive ion, normalized initial density of electrons, and normalized initial density of positive ions, respectively, Z d , B 0 , and m d as the charge number of a dust particle, strength of the static magnetic field, and mass of a dust particle, respectively. It is also found that the two solitons are always parallel during the propagation on the x − y , x − t , and y − t planes, where x , y , and z are the scaled spacial coordinates, and t is the retarded time. Upon the introduction of the driving force Γ ( t ) , both the developed and weak chaotic motions as well as the effect of Γ ( t ) are explored. Via the phase projections and power spectra, we find the difference between the two chaotic motions roots in the relative magnitude of nonlinearity and external force. Increasing the frequency of the external force or the strength of the damped term can weaken the chaotic motions of such a forced model.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
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