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1.
The mixed spin-1/2 and spin-1 Ising chain with both longitude and transverse single-ion anisotropies Dz and Dx is solved exactly by means of a mapping to the spin-1/2 Ising chain with the alternating transverse fields and the Jordan-Wigner transformation. The analytical expressions of the quasi-particles' spectra Λk, the minimal energy gap Δ0 for exciting a fermion quasi-particle, the minimal energy gap Δh for exciting a hole, and the ground state energy are obtained. The phase diagram of the ground state is also given. The results show that when Dz?0 for any finite value of Dx, there is no quantum critical point and the ground state is always in a spin ordered phase disregard of the boundary condition in the present system. 相似文献
2.
In this paper, we study the equilibrium properties of polymer chains end-tethered to a fluid membrane. The loss of conformational
entropy of the polymer results in an inhomogeneous pressure field that we calculate for Gaussian chains. We estimate the effects
of excluded volume through a relation between pressure and concentration. Under the polymer pressure, a soft surface will
deform. We calculate the deformation profile for a fluid membrane and show that close to the grafting point, this profile
assumes a cone-like shape, independently of the boundary conditions. Interactions between different polymers are also mediated
by the membrane deformation. This pair-additive potential is attractive for chains grafted on the same side of the membrane
and repulsive otherwise.
Received 20 April 2000 相似文献
3.
A crystal field (CF) investigation of the magnetic properties and heat capacities of RCuAs2 (R=Pr, Nd, Sm, Tb, Dy, Ho, Er and Yb) has been carried out using the observed average magnetic susceptibilities (1.8-300 K) of the title compounds. The CF parameters proposed for the systems show a systematic variation throughout the rare-earth series. Other physical properties dependent on the CF are also computed and compared with available experimental data. The experimental heat capacity data reported for a limited range of temperature agree well with computed heat capacity for all the compounds (except SmCuAs2 and YbCuAs2). CF J mixing was found to be appreciable for all the samples except YbCuAs2. 相似文献
4.
Received: 18 September 1998/Accepted: 22 September 1998 相似文献
5.
An annealing study of the 0.8 eV photoluminescence band in LEC GaAs has been performed, using a combination of 10 min annealing steps over a temperature range of 800–1100° C and one hour furnace annealing steps at 500–700° C. Results show that the defect responsible for the luminescence is stable in bulk material under all annealing conditions that have been investigated. In combination with earlier results, this demonstrates a stability of the defect to temperatures in excess of 900° C and indicates a parallel with the annealing behavior of the 0.67 eV band in semi-insulating GaAs. The observed annealing behavior is very different in the near-surface region, indicating an important role of As out-diffusion. 相似文献
6.
The existence and stability under linear perturbations of closed timelike geodesics (CTG) in Bonnor–Ward spacetime is studied in some detail. Regions where the CTG exist and are linearly stable are exhibited. 相似文献
7.
Atom interferometry gravity-gradiometer for the determination of the Newtonian gravitational constant G 总被引:1,自引:0,他引:1
A. Bertoldi G. Lamporesi L. Cacciapuoti M. de Angelis M. Fattori T. Petelski A. Peters M. Prevedelli J. Stuhler G. M. Tino 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,40(2):271-279
We developed a gravity-gradiometer based on atom interferometry for the determination of the Newtonian gravitational constant
G.
The apparatus, combining a Rb fountain, Raman interferometry and a juggling scheme for fast launch of two atomic clouds, was
specifically
designed to reduce possible systematic effects. We present instrument performances and preliminary results for the measurement
of G with a relative uncertainty of 1%. A discussion of projected accuracy for G measurement using this new scheme shows
that the results of the experiment will be significant to discriminate between previous inconsistent values. 相似文献
8.
Li Chen BangNing Mao YuBo Wang LiMing Wang BaiLiang Pan 《Optics Communications》2008,281(5):1211-1216
A self-consistent model has been developed to simulate the kinetics of alternate oscillation of self-terminating and recombination lasers in univalent ions of strontium excited by the high-repetition-rate (HRR) pulsed discharge. Photoelectric pulse waveforms predicted by the model are in good agreement with the experimental measurement. The model also gives temporal behaviors of long-life particles, the population densities of upper and lower laser levels and the electron temperature (Te) in He-Sr discharge plasma. The emission process of the two laser alternate oscillations, the characteristic of the laser pulse width and the population inversion mechanics are also analyzed. 相似文献
9.
U. Yurtsever D. Strekalov J.P. Dowling 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):365-371
A quantum gravity-gradiometer consists of two spatially separated ensembles of atoms interrogated by pulses of a common laser
beam. The laser pulses cause the probability amplitudes of atomic ground-state hyperfine levels to interfere, producing two,
motion-sensitive, phase shifts, which allow the measurement of the average acceleration of each ensemble, and, via simple
differencing, of the acceleration gradient. Here we propose entangling the quantum states of atoms from the two ensembles
prior to the pulse sequence, and show that entanglement encodes their relative acceleration in a single interference phase
which can be measured directly, with no need for differencing.
Received 6 June 2002 / Received in final form 25 October 2002 Published online 28 January 2003 相似文献
10.
Electron paramagnetic resonance and optical absorption spectra of Cr ions in cadmium phosphate glass
R.V.S.S.N. Ravikumar Ryuichi KomatsuKo. Ikeda A.V. ChandrasekharB.J. Reddy Y.P. ReddyP.S. Rao 《Solid State Communications》2003,126(5):251-253
EPR and optical absorption investigations of chromium doped cadmium phosphate glass are carried out. Crystal field, spin-Hamiltonian and bonding parameters are evaluated. From the results and analyses of the EPR and optical studies, the site symmetry of Cr3+ ion in the glass is ascribed to a distorted octahedron. The bonding parameters suggest the ionic nature of Cr3+ ion with the ligands. 相似文献