Spin melting and refreezing driven by uniaxial compression on a dipolar hexagonal plate

We investigate freezing characteristics of a finite dipolar hexagonal plate by the Monte Carlo simulation. The hexagonal plate is cut out from a piled triangular lattice of three layers with FCC-like (ABCABC) stacking structure. In the present study an annealing simulation is performed for the dipolar plate uniaxially compressed in the direction of layer-piling. We find spin melting and refreezing driven by the uniaxial compression. Each of the melting and refreezing corresponds one-to-one with a change of the ground states induced by compression. The freezing temperatures of the ground-state orders differ significantly from each other, which gives rise to the spin melting and refreezing of the present interest. We argue that these phenomena are originated by a finite size effect combined with peculiar anisotropic nature of the dipole-dipole interaction.Comment: Proceedings of the Highly Frustrated Magnetism (HFM2006) conference. To appear in a special issue of J. Phys. Condens. Matte

Prediction of pressure-induced red shift of f->d(t2g) excitations in Cs2NaYCl6:Ce(3+) and its connection with bond length shortening

Quantum chemical calculations including embedding, scalar relativistic, and dynamic electron correlation effects on Cs2NaYCl6:(CeCl6)3- embedded clusters predict: (i) red shifts of the 4f->5d(t2g) transition with pressure and (ii) bond length shortening upon 4f->5d(t2g) excitation. Both effects are found to be connected which suggests that new high pressure spectroscopic experiments could reveal the sign of the bond length change.Comment: 6 pages text; 1 table; 3 figures; to be published in J.Chem.Phy

Fractal Structure in Multiparticle Production in e+e- Annihilations at 29 GeV

The fractal structure in multiparticle production in e{sup +}e{sup {minus}} annihilations at 29 GeV has been studied using the HRS detector at PEP. Very high fractal moments have been measured and their implications are discussed in terms of an {alpha}-model and a thermodynamical model. Two-dimensional fractal moments in the rapidity and azimuthal angle space have also been measured and the results are compared to the Lund string model predictions. 6 refs., 2 figs