Magnetism and heterogeneity of Co in anatase Co:TiO₂ magnetic semiconductor

Using x-ray magnetic circular dichroism XMCD, x-ray absorption spectroscopy XAS, and energy filtered transmission electron microscopy, we provide evidence for a heterogeneous Co distribution in anatase Co:TiO2 magnetic semiconductor having a low Co concentration 1.4 at. %. Multiplet structure due to Co2+ is observed in XAS spectra, but suppressed due to the coexistence of metallic Co clusters and substitutional Co ions, whereas XMCD spectra resemble metallic Co. The presence of Co2+ can be correlated with earlier observations of impurity band conduction and Kondo behavior, whereas metallic Co clusters contribute to the ferromagnetism and anomalous Hall effect

Decoupling in the 1D frustrated quantum XY model and Josephson junction ladders: Ising critical behavior

A generalization of the one-dimensional frustrated quantum XY model is considered in which the inter and intra-chain coupling constants of the two infinite XY (planar rotor) chains have different strengths. The model can describe the superconductor to insulator transition due to charging effects in a ladder of Josephson junctions in a magnetic field with half a flux quantum per plaquette. From a fluctuation-effective action, this transition is expected to be in the universality class of the two-dimensional classical XY-Ising model. The critical behavior is studied using a Monte Carlo transfer matrix applied to the path-integral representation of the model and a finite-size-scaling analysis of data on small system sizes. It is found that, unlike the previous studied case of equal inter and intra-chain coupling constants, the XY and Ising-like excitations of the quantum model decouple for large interchain coupling, giving rise to pure Ising model critical behavior for the chirality order parameter and a superconductor-insulator transition in the universality class of the 2D classical XY model.Comment: 15 pages with figures, RevTex 3.0, INPE-93/00

Chaotic inflation in Jordan frame supergravity

We consider the inflationary scenario with non-minimal coupling in 4D Jordan frame supergravity. We find that there occurs a tachyonic instability along the direction of the accompanying non-inflaton field in generic Jordan frame supergravity models. We propose a higher order correction to the Jordan frame function for solving the tachyonic mass problem and show that the necessary correction can be naturally generated by the heavy thresholds without spoiling the slow-roll conditions. We discuss the implication of the result on the Higgs inflation in NMSSM.Comment: 16 pages, no figures, version to be published in JCA

Density profile of a strictly two-dimensional Bose gas at finite temperature

We study a Bose-condensed gas at finite temperature, in which the particles of the condensate and of the thermal cloud are constrained to move in a plane under radial harmonic confinement and interact via strictly two-dimensional collisions. The coupling parameters are obtained from a calculation of the many-body T-matrix and decreases as temperature increases through a dependence on the chemical potential and on the occupancy of excited states. We discuss the consequences on the condensate fraction and on the density profiles of the condensed and thermal components as functions of temperature, within a simplified form of the two-fluid model.Comment: 12 pages, 4 figure

Preliminary test of group acceptance and commitment therapy on obsessive-compulsive disorder for patients on optimal dose of selective serotonin reuptake inhibitors

The aim of this study was to investigate the effects of adding group acceptance and commitment therapy (ACT) to adults diagnosed with obsessive compulsive disorder (OCD) who were already on an optimal dose of selective serotonin reuptake inhibitors (SSRIs). Forty-six Iranian women, on SSRIs, were randomized to group ACT + SSRI or continued SSRI conditions. SSRI dosages stayed stable during the study. Assessments included the Structured Clinical Interview (SCID-I), Yale-Brown Obsessive-Compulsive Scale Self report (Y-BOCS-SR), Beck Depression Inventory-II (BDI-II), Ruminative Response Scale (RRS), and Acceptance and Action Questionnaire (AAQ-II). The results showed significant reductions on the Y-BOCS-SR and BDI-II in both conditions at posttreatment with significantly greater reductions in the ACT + SSRI condition at follow-up. The RRS and AAQ-II saw significant improvements in the ACT + SSRI condition at posttreatment and follow-up compared to the SSRI condition. Results provide cross-cultural support for group ACT as a treatment for OCD and as a successful adjunct to SSRI treatment. © 201

Spin Motion in Electron Transmission through Ultrathin Ferromagnetic Films Accessed by Photoelectron Spectroscopy

Ab initio and model calculations demonstrate that the spin motion of electrons transmitted through ferromagnetic films can be analyzed in detail by means of angle- and spin-resolved core-level photoelectron spectroscopy. The spin motion appears as precession of the photoelectron spin polarization around and as relaxation towards the magnetization direction. In a systematic study for ultrathin Fe films on Pd(001) we elucidate its dependence on the Fe film thickness and on the Fe electronic structure. In addition to elastic and inelastic scattering, the effect of band gaps on the spin motion is addressed in particular.Comment: 4 pages, 5 figure

Catalysis with inorganic membranes

Catalytic inorganic membranes are among the most challenging and intriguing porous materials. Consisting of a thin film of mesoporous or microporous inorganic material deposited on a macroporous material, catalytic membranes are multifunctional materials that must be engineered for both chemical and physical properties. New approaches to carrying out chemical reactions are possible by tailoring the membrane catalytic activity and selectivity, permselectivity, and other thin film properties. Readers are referred to several recent reviews of inorganic membranes, in particular, Zaspalis and Burggraaf, Armor, Gellings and Bouwmeister, Hsieh, Stoukides, and Tsotsis et al. Inorganic membranes are most conveniently classified according to pore size (see introductory article). Of particular importance is the ratio of the pore size to the molecular mean free path (MFP). Decreasing pore dimensions lead to increased selectivity with corresponding loss of permeability. Macroporous membranes have a pore size much larger than the MFP, leading to molecular (bulk) diffusion or viscous flow. Knudsen diffusion dominates in the mesoporous regime, where the pore size is comparable to the MFP. In addition, surface diffusion of the molecules along the pore walls may contribute, leading to an enhanced flux of the adsorbed species along the walls. The microporous regime is encountered when the pore size is comparable to the molecules. This regime makes possible much higher permselectivities, which depend on both molecular size and specific interactions with the solid. Finally, in dense membranes, molecular transport occurs through a solution-diffusion mechanism, which also involves specific interactions between the solute and membrane

Spatial labeling in a two-photon interferometer

Quantum Matter and Optic