HBT and Fluctuations: Recent Results

We give an overview of the latest results of HBT and fluctuations studies in heavy ion collisions presented during the Quark Matter 2001 Conference.Comment: Contribution to Quark Matter 2001 Conferenc

Turning a Band Insulator Into an Exotic Superconductor

Understanding exotic, non s--wave--like states of Cooper pairs is important and may lead to new superconductors with higher critical temperatures and novel properties. Their existence is known to be possible but has always been thought to be associated with non--traditional mechanisms of superconductivity where electronic correlations play an important role. Here we use a first principles linear response calculation to show that in doped Bi$_{2}$Se$_{3}$ an unconventional p--wave--like state can be favored via a conventional phonon--mediated mechanism, as driven by an unusual, almost singular behavior of the electron--phonon interaction at long wavelengths. This may provide a new platform for our understanding superconductivity phenomena in doped band insulators.Comment: Published versio

Computational Design of Axion Insulators Based on 5d Spinels Compounds

Based on density functional calculation with LDA+U method, we propose that hypothetical Osmium compounds such as CaOs2O4 and SrOs2O4 can be stabilized in the geometrically frustrated spinel crystal structure. They also show some exotic electronic and magnetic properties in a reasonable range of on-site Coulomb correlation U such as ferromagnetism and orbital magnetoelectric effect characteristic to Axion electrodynamics. Other electronic phases including 3D Dirac metal and Mott insulator exist and would make perspective 5d spinels ideal for applications.Comment: 5 pages, 3 figure

Origin of Low Thermal Conductivity in Nuclear Fuels

Using a novel many-body approach, we report lattice dynamical properties of UO2 and PuO2 and uncover various contributions to their thermal conductivities. Via calculated Grueneisen constants, we show that only longitudinal acoustic modes having large phonon group velocities are efficient heat carriers. Despite the fact that some optical modes also show their velocities which are extremely large, they do not participate in the heat transfer due to their unusual anharmonicity. Ways to improve thermal conductivity in these materials are discussed.Comment: 4 pages, 3 figures, 1 tabl