The precise crystal symmetry, and hence the emergence of electric polarization, still remains an open question in multiferroic $R$Mn${}_{2}$O${}_{5}$ ($R$=rare earth, Bi, Y). While previous diffraction studies have indicated centrosymmetric space group $P\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}m$, atomic displacement allowing for polarization would require a nonce...

We have studied the phase transitions in atomic clusters by molecular dynamics simulation, assuming Lennard-Jones interatomic pair potential. Calculations are performed by DAP parallel computer. The results are analyzed by simulating their orientational distribution plots (dot-plot), and neutron diffraction patterns. It is shown that all the main features of the bulk phase transitions are e...

We report the lattice site and symmetry of optically active Dy3+ and Tm3+ implanted Si. Local symmetry was determined by fitting crystal field parameters (CFPs), corresponding to various common symmetries, to the ground state splitting determined by photoluminescence measurements. These CFP values were then used to calculate the splitting of every J manifold. We find that ...