In the present work, the exact diagonalization method had been implemented to calculate the ground state energy of shallow donor impurity located at finite distance along the growth axis in GaAs/AlGaAs heterostructure in the presence of a magnetic field taken to be along z direction. The impurity binding energy of the ground state had been calculated as a function of confining frequency and mag...

The effect of impurities which induce local interlayer tunneling in bilayer exciton condensates is discussed. We show that a localized single-fermion bound state emerges inside the gap for any strength of impurity scattering and calculate the dependence of the impurity state energy and wave function on the potential strength. We show that such an impurity-induced single-fermion state enhances t...

Resonant soft X-ray Raman scattering measurements on NiO have been made at photon energies across the Ni 2p absorption edges. The details of the spectral features are identified as Raman scattering due to d−d and charge-transfer excitations. The spectra are interpreted within the single impurity Anderson model, including multiplets, crystal-field and charge-transfer effects. At threshold excita...

We review the progress of nonmagnetic impurity doping studies on Fe-based superconductors. On the theoretical side, two highly promising candidates for the pairing symmetry order parameter, i.e. the multi-gap s++ and s± wave models, have been proposed but continuously debated. The debate arises because of the complex gap structure and exceptional magnetic and metallic behaviors of Fe-based supe...

An approximate ground state of the Anderson-Friedel impurity problem is presented in a very compact form. It requires solely the optimization of two localized electron states and consists of four Slater states Slater determinants . The resulting singlet ground-state energy lies far below the Anderson mean-field solution and agrees well with the numerical results by Gunnarsson and Schönhammer, w...

Hydrothermal and commercial barium titanate powders were examined for undesirable impurity phases. Compositional differences in the powder were evaluated using x-ray diffraction ( XRD ), x-ray fluorescence ( XRF ), and x-ray photoelectron spectroscopy (XPS). A brium-rich impurity phase, virtually undetectable by XRD, was detected via XPS. Barium impurity phase peaks were detected at binding ene...

We study a model of a d-wave superconductor with strong potential scatterers in the presence of antiferromagnetic correlations and apply it to experimental nuclear magnetic resonance NMR results on Zn impurities in the superconducting state of YBa2Cu3O7− . We then focus on the contribution of impurity-induced paramagnetic moments, with Hubbard correlations in the host system accounted for in Ha...

Impurity effective mass in superfluid 4He I.O.Vakarchuk, V.V.Babin Ivan Franko Lviv State University, Department for Theoretical Physics, 12 Drahomanov St., UA-290005 Lviv, Ukraine Received June 9, 1998 The system of bose liquid + impurity is considered. The energy spectrum, as well as effective mass of impurity is calculated. For the case of an 3He atom in superfluid 4He numerical calculations...

We consider the screening of a magnetic impurity in a dx2−y2 wave superconductor. The properties of the dx2−y2 state lead to an unusual behavior in the impurity magnetic susceptibility, the impurity specific heat and in the quasiparticle phase shift which can be used to diagnose the nature of the condensed state. We construct an effective theory for this problem and show that it is equivalent t...

We study a two-impurity, two-channel Kondo model, focusing on the behavior near the limit of two independent impurities. We find that significant departures from the independent regime develop below a crossover temperature which scales approximately as the tenth power of a parity asymmetry. The one-impurity, two-channel Kondo model has been the object of much renewed interest recently [ i ] . T...