In this paper we study an impurity in Bose-Einstein-Condensate system at T = 0K and suppose the contact forms for boson-boson and boson-impurity interactions. Using Bogoliubov theory and a further approximation corresponding to only think over the forward scattering of impurity by bosons, we derive a reduced Hamiltonian whose form is the same as the Fröhlich Hamiltonian for large polaron. By us...

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...

A redox chemical looping process is investigated as an add-on deoxygenation unit for the production of high-purity nitrogen from air using pressure swing adsorption systems. material screening study indicated non-stoichiometric perovskite oxide Sr0.8Ca0.2FeO3−δ a promising candidate with fast kinetics and 75% greater gravimetric oxygen capacity compared to state-of-the-art SrFeO3 at desired con...

The Large Helical Device (LHD) and Wendelstein 7-X (W7-X, under construction) are experiments specially designed to demonstrate long pulse (quasi steady-state) operation, which is an intrinsic property of Stellarators and Heliotrons. Significant progress was made in establishment of high performance plasmas. A crucial point is the increasing impurity confinement towards high density as observed...

The influence of irradiation with white light on the permeability at 77 K is investigated on p-type yttrium iron garnet single crystals with Pb impurity. Theexistence of an irreversible photo-magnetic effect and photo-accelerated disaccommodation is demonstrated in p-type YIG. These effects are explained by a modified two center model in which Fe4+ plays an important role.

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...

n-type float-zone silicon grown in a nitrogen atmosphere contains defects which are activated by temperatures between 450 and 700 °C. We use deep level transient spectroscopy (DLTS) to study the nature of these impact content polysilicon feed stock type. find four dominant DLTS peaks with activation energies E na = 0.16 eV (E1), 0.21 (E2), 0.34 (E4), 0.64 (E6). tentatively assign two E1 E2 sing...

A dynamic density-matrix renormalisation group approach to the spectral properties of quantum impurity problems is presented. The method is demonstrated on the spectral density of the flat-band symmetric single-impurity Anderson model. We show that this approach provides the impurity spectral density for all frequencies and coupling strengths. In particular, Hubbard satellites at high energy ca...

Trace impurity transport in tokamaks is studied using an electrostatic, collisionless fluid model for Ion-Temperature-Gradient (ITG) and Trapped-Electron (TE) mode driven turbulence in the presence of radio frequency (rf) fields in the ion cyclotron range of frequencies, and the results are compared with neoclassical predictions. Two separate effects of the rf field on ITG/TE-mode stability and...

Static and dynamic frictional phenomena at the interface with random impurities are investigated in a two-chain model with incommensurate structure. Static frictional force is caused by the impurity pinning and/or by the pinning due to the regular potential, which is responsible for the breaking of analyticity transition for impurity-free cases. It is confirmed that the static frictional force ...