Authors:Qing-Hu Zhong et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, the interface phonons in a core-shell quantum dot are theoretically studied by a resonant Raman scattering (RRS) process. Fröhlich electron–phonon interaction is considered in the framework of the dielectric continuum approach. The Raman peaks are found to be sensitive to the size of strongly confined shell. The shift of the Raman resonant peaks is a consequence of the change of observed dispersion of the phonon frequency. The Raman intensity changes in the system with shell thickness, originating from the competition between the spacial distribution of electron wave function and the number of phonons joining in the RRS process. The analysis of the Raman spectra gives a physical explanation to the size-selective nature of the Raman process and some experimental results. PubDate: Thu, 21 Aug 2014 08:20:22 GMT

Authors:Ren-Jie Zhang et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, we investigate the dynamics of quantum entanglement of a two-qubit quantum system coupled with generalized amplitude damping (GAD) channel of nonzero temperature in noninertial frames. The results show that the concurrence decreases with the increase of acceleration and channel parameter r has a decisive impact on the entanglement. Accidentally, we manifest the inequivalence of the quantization for a Dirac field under the GAD channel in the noninertial frames. PubDate: Thu, 21 Aug 2014 08:20:21 GMT

Authors:Nguyen Van Hung et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, high-order expanded anharmonic effective potential and Debye–Waller factors in X-ray absorption fine structure (XAFS) of hcp crystals have been studied based on classical anharmonic correlated Einstein model. Here XAFS Debye–Waller factors are presented in terms of cumulant expansion up to the fourth order and their analytical expressions have been derived based on classical statistical theory. They contain the parameters of a derived high-order anharmonic effective potential that takes into account all nearest neighbors of absorber and backscattering atoms, where Morse potential is assumed to describe interatomic interaction included in this derived anharmonic effective potential. The dependence of the derived cumulants on atomic vibrations is described by their proportionality to the correlated Einstein frequency. This model avoids full lattice dynamical calculations yet provides good agreement of numerical results for Zn and Cd with experiment at several temperatures. PubDate: Thu, 21 Aug 2014 08:20:21 GMT

Authors:Dan Liu et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, extraction efficiency in simplified and layered light-emitting diodes (LEDs) of GaN photonic crystal with periodic air holes is studied by three-dimensional finite-difference time-domain method. Photonic band structures of the photonic crystal are obtained by plane-wave expansion method. The results about simplified GaN-LED show that extraction efficiency is very sensitive to the structure parameters tuning, and increases considerably inside the transverse-electric-like gap region. A maximum extraction efficiency above 90% can be achieved. The effects of the PC thickness and air-hole radius on relative extraction efficiency of layered GaN-LED are analyzed. They show optimal values to obtain high relative extraction efficiency. PubDate: Thu, 21 Aug 2014 08:20:18 GMT

Authors:Mikhail B. Belonenko et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, we investigate the peculiar features of the tunneling contact between a superlattice and a non-Fermi quantum liquid. The imaginary part of the Green functions are responsible for the non-Fermi liquid density of states. The Green functions have been derived within the framework of the anti-de Sitter/conformal field theory correspondence. PubDate: Thu, 21 Aug 2014 08:20:18 GMT

Authors:Nabyendu Das Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, we present a theory of phase transition in quantum critical paraelectrics in presence of quenched random-Tc disorder using replica trick. The effects of disorder induced locally ordered regions and their slow dynamics are included by breaking the replica symmetry at vector level. The occurrence of a mixed phase at any finite value of disorder strength is argued. A broad power law distribution of quantum critical points and and its finite temperature consequences are predicted. Results are interesting in the context of a certain class of disordered materials near quantum phase transition. PubDate: Thu, 21 Aug 2014 08:20:18 GMT

Authors:Ondrej Hudak et al Abstract: Modern Physics Letters B, Volume 28, Issue 21, 20 August 2014.
In this paper, we study the behavior of the particle in the paraelectric phase near the bulk critical temperature (a = 0) (in our units) and near the particle critical temperature (ad) using the fluctuation–dissipation theorem through the power spectrum density S(ω) at zero frequency ω = 0 in the particle. This power spectrum density is found here to have three regimes as concerning the temperature dependence for a given particle diameter. The first one is above the bulk critical temperature, the second one is at the bulk critical temperature and the third is below the bulk critical temperature and above the particle critical temperature. Decreasing temperature fluctuations of the order parameter (polarization) change from the bulk-like to the particle-like due to particle form. Divergency of the bulk spectrum density Sb(0) at the bulk critical temperature a = 0 is compensated in the particle by the contribution ≈a2 due to the particle form. The power spectrum density S(0) near the particle critical temperature diverges with the exponent 2, we obtain , where Tc, d is the particle critical temperature in the temperature variable T. Our results are new and are exact within the model used. PubDate: Thu, 21 Aug 2014 08:20:16 GMT

Authors:Xiaoshan Xu et al Abstract: Modern Physics Letters B, Ahead of Print.
Hexagonal ferrites (h-RFeO3, R = Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature multiferroicity and the predicted magnetoelectric effect, h-RFeO3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic and magnetoelectric properties of h-RFeO3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties. PubDate: Wed, 13 Aug 2014 09:18:45 GMT