Zn-doping effect on the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}CuO_{6+\delta} single crystals

We report the magnetotransport properties of Bi_{2}Sr_{2-x}La_{x}Cu_{1-z}Zn_{z}O_{6+\delta} (Zn-doped BSLCO) single crystals with z of up to 2.2%. Besides the typical Zn-doping effects on the in-plane resistivity and the Hall angle, we demonstrate that the nature of the low-temperature normal state in the Zn-doped samples is significantly altered from that in the pristine samples under high magnetic fields. In particular, we observe nearly-isotropic negative magnetoresistance as well as an increase in the Hall coefficient at very low temperatures in non-superconducting Zn-doped samples, which we propose to be caused by the Kondo scattering from the local moments induced by Zn impurities.Comment: 4 pages, 4 figures, final version (one reference added), published in Phys. Rev.

Combination Rules, Charge Symmetry, and Hall Effect in Cuprates

The rule relating the observed Hall coefficient to the spin and charge responses of the uniform doped Mott insulator is derived. It is essential to include the contribution of holon and spinon three-current correlations to the effective action of the gauge field. In the vicinity of the Mott insulating point the Hall coefficient is holon dominated and weakly temperature dependent. In the vicinity of a point of charge conjugation symmetry the holon contribution to the observed Hall coefficient is small: the Hall coefficient follows the temperature dependence of the diamagnetic susceptibility with a sign determined by the Fermi surface shape. NOTE: document prepared using REVTEX. (3 Figs, not included, available on request from: [email protected])Comment: 8 page

Current-induced spin-wave excitations in a single ferromagnetic layer

A new current induced spin-torque transfer effect has been observed in a single ferromagnetic layer without resorting to multilayers. At a specific current density of one polarity injected from a point contact, abrupt resistance changes due to current-induced spin wave excitations have been observed. The critical current at the onset of spin-wave excitations depends linearly on the external field applied perpendicular to the layer. The observed effect is due to current-driven heterogeneity in an otherwise uniform ferromagnetic layer.Comment: 12 pages, 4 figure

Intracule Functional Models I. Angle-corrected correlation kernels

We explore the merits of applying a simple angle-dependent correction to the correlation kernel within the framework of Hartree–Fock–Wigner theory. Based on numerical results for the first eighteen atoms, we conclude that such a correction offers a significant improvement over the action kernel that we and others have explored previously

Dynamical mean-field equations for strongly interacting fermionic atoms in a potential trap

We derive a set of dynamical mean-field equations for strongly interacting fermionic atoms in a potential trap across a Feshbach resonance. Our derivation is based on a variational ansatz, which generalizes the crossover wavefunction to the inhomogeneous case, and the assumption that the order parameter is slowly varying over the size of the Cooper pairs. The equations reduce to a generalized time-dependent Gross-Pitaevskii equation on the BEC side of the resonance. We discuss an iterative method to solve these mean-field equations, and present the solution for a harmonic trap as an illustrating example to self-consistently verify the approximations made in our derivation.Comment: replaced with the published versio

Fermionic superfluidity: From high Tc superconductors to ultracold Fermi gases

We present a pairing fluctuation theory which self-consistently incorporates finite momentum pair excitations in the context of BCS--Bose-Einstein condensation (BEC) crossover, and we apply this theory to high $T_c$ superconductors and ultracold Fermi gases. There are strong similarities between Fermi gases in the unitary regime and high Tc superconductors. Here we address key issues of common interest, especially the pseudogap. In the Fermi gases we summarize recent experiments including various phase diagrams (with and without population imbalance), as well as evidence for a pseudogap in thermodynamic and other experiments.Comment: Expanded version, invited talk at the 5th International Conference on Complex Matter -- Stripes 2006, 6 pages, 6 figure

Charge Localization from Local Destruction of Antiferromagnetic Correlation in Zn-doped YBa2Cu3O7-d

The in-plane normal-state resistivity of Zn-doped YBa2Cu3O7-d single crystals is measured down to low temperatures by suppressing superconductivity with magnetic fields up to 18 T. Substitution of Cu with Zn in the CuO2 planes is found to induce carrier localization at low temperatures in "clean" samples with kF l > 5, where the mean free path l is larger than the electron wave length and thus localization is not normally expected. The destruction of the local antiferromagnetic correlation among Cu spins by Zn is discussed to be the possible origin of this unusual charge localization.Comment: 4 pages of LaTeX (revtex and epsf) including 4 postscript figure

Localization and Anomalous Transport in a 1-D Soft Boson Optical Lattice

We study the dynamics of Bose-Einstein condensed atoms in a 1-D optical lattice potential in a regime where the collective (Josephson) tunneling energy is comparable with the on-site interaction energy, and the number of particles per lattice site is mesoscopically large. By directly imaging the motion of atoms in the lattice, we observe an abrupt suppression of atom transport through the array for a critical ratio of these energies, consistent with quantum fluctuation induced localization. Directly below the onset of localization, the frequency of the observed superfluid transport can be explained by a phonon excitation but deviates substantially from that predicted by the hydrodynamic/Gross-Pitaevskii equations.Comment: 14 pages, 5 figure