Anomalous proximity effect in d-wave superconductors

The anomalous proximity effect between a d-wave superconductor and a thin disordered normal layer is studied theoretically in the framework of Eilenberger equations. It is shown that disorder of the quasiparticle reflection from this thin layer leads to the formation of an s-wave component localized near the boundary. The angular and spatial structure of the pair potential near the interface is studied. Pis’ma Zh. éksp. Teor. Fiz. 67, No. 7, 478–483 (10 April 1998) Published in English in the original Russian journal. Edited by Steve Torstveit.     

Triplet proximity effect in FSF trilayers

We study the critical temperature T _c of FSF trilayers (F is a ferromagnet, S is a singlet superconductor), where the triplet superconducting component is generated at noncollinear magnetizations of the F layers. An exact numerical method is employed to calculate T _c as a function of the trilayer parameters, in particular, mutual orientation of magnetizations. Analytically, we consider limiting cases. Our results determine the conditions necessary for the existence of recently investigated odd triplet superconductivity in SF multilayers.     

Polarization of thallium atoms produced in molecular photodissociation: experiment and theory

A study has been made of the oriented ground state Tl(6² P _1/2) atoms produced in the photodissociation of TlBr molecules by circularly polarized 266-nm laser light. A significant degree of atomic orientation (15%) has been measured in the experiment which corresponds to the initial degree of orientation of 37%. A high value of depolarization cross section (210 Ų) for the oriented Tl atoms colliding with TlBr molecules has been also observed. The obtained experimental results have been treated theoretically. We present a general quantum mechanical theory of the orientation phenomenon in which all possible nonadiabatic interactions as well as molecular rotation are properly treated. The application of the theory to the case of TlBr photodissociation allowed to understand the obtained experimental results and to evaluate the probability of the earlier unknown radial nonadiabatic transition in the decaying molecule.     

Chromium ion incorporation in the crystal structure of BGO

Comprehensive investigations have been performed by EPR and optical spectroscopy for Bi₃GeO₄ crystals doped with chromium ions. It is demonstrated that the known optical absorption spectrum for chromium ions, specifically, the triplet in the region 600–900 nm has an analog in the EPR spectra — the center with electron spin S = 1. The spectrum is described by the spin-Hamiltonian with the parameters D = 550 G, E = 10 G, g _xx = g _yy = 1.915, g _zz = 1.932. The EPR spectrum is dictated by Cr⁴⁺ incorporation at the germanium sites. Luminescence observed in the region 1.2–1.7 μm is also caused by transitions of Cr⁴⁺ with tetrahedral surroundings to germanium sites. Original Russian Text Copyright ? 2005 N. V. Chernei, V. A. Nadolinnyi, N. V. Ivannikova, V. A. Gusev, I. N. Kupriyanov, V. N. Shlegel, and Ya. V. Vasiliev __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 3, pp. 444–450, May–June, 2005.     

Refinement of Lower Bounds of the Chromatic Number of a Space with Forbidden One-Color Triangles

Mathematical Notes - The present paper deals with estimates of the chromatic number of a space with forbidden one-color triangles. New lower bounds for the quantity under study, which are sharper...     

Enhancement of electromagnetically induced transparency in room temperature alkali metal vapor

Electromagnetically induced transparency (EIT) has led to several quantum optics effects such as lasing without inversion or squeezed light generation. More recently quantum memories based on EIT have been experimentally implemented in different systems such as alkali metal atoms. In this system the excited state of the optical transition splits into several sublevels due to the hyperfine interaction. However, most of the theoretical models used to describe the experimental results are based on a Λ-system with only one excited state. In this article, we present a theoretical model for the Λ-type interaction of two light, fields and an atomic system with multiple excited state. In particular we show that if the control and probe fields are orthogonally circularly polarized the EIT effect in an alkali-metal vapor can almost disappears. We also identify the reasons of this reduction and propose a method to recover the transparency via velocity selective optical pumping.     

Resonant tunneling in superconducting structures with <Emphasis Type="Italic">s</Emphasis> and <Emphasis Type="Italic">d</Emphasis> symmetry of order parameter

Resonant tunneling processes are studied in superconducting junctions of low transparency with the order parameter of the electrodes of different symmetry. A general equation of the resonant current is derived within the Green’s function formalism for the junctions of arbitrary dimensionality. The phase dependence of the supercurrent averaged over the set of localized states is analyzed for superconducting junctions with an isotropic order parameter. A numerical analysis of the resonant current transport in junctions with high-T _c superconducting electrodes with the d symmetry of the order parameter was carried out.     

Degenerate ground state in a mesoscopic YBa2Cu3O(7-x) grain boundary Josephson junction

We have measured the current-phase relationship I(varphi) of symmetric 45 degrees YBa2Cu3O7-x grain boundary Josephson junctions. Substantial deviations of the Josephson current from conventional tunnel-junction behavior have been observed: (i) The critical current exhibits, as a function of temperature T, a local minimum at a temperature T*. (ii) At T approximately T*, the first harmonic of I(phi) changes sign. (iii) For T相似文献