摘要:

AbstractThe time‐differential perturbed angular correlation for111Cd nuclei has been measured after111In implantation into polycrystalline TiO2. The observed perturbation functions are characterized by a well‐defined electric field gradient with the quadrupole coupling constant νQ= 105(1) MHz and the asymmetry parameter η = 0.18(1). We attribute these hyperfine parameters to111Cd on the (distorted) substitutional cation site in rutile. The PAC results are compared with those in SnO2rutile as well as with X‐ray diffraction, RBS channeling experiments and point charge model calculations including relaxation of the probe atom surr

ISSN:0003-3804    

DOI:10.1002/andp.19925040302

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractMacroscopic tensile and compressive mechanical stresses in the film plane are observed during the growth of amorphous binary‐alloy films of ZrCo and TbCo prepared by the condensation of the metal vapours from two electron‐beam evaporators. The mechanical stress is measured by a capacitive cantilever beam technique. Both kinds of stresses are affected by composition and substrate temperature, but the compressive stress additionally depends on the film thickness, evaporation rate and substrate material. The results are discussed in terms of a model for the growth of amorphous films published earl

ISSN:0003-3804    

DOI:10.1002/andp.19925040303

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractIn a gaseous helium or hydrogen target slow muons or antiprotons are captured into orbits with a high principal quantum number (n= 15 to 50) to form (μ−α)+ions, (pα)+ions, or (pp) atoms respectively. In the subsequent deexcitation process Stark mixing of the intermediary states plays an important role. The successful Mainz Cascade Model assumed Δn= 0 for the Stark transitions, although formally no such selection rule exists. This note examines the reasons why Δn≠ 0 Stark transitions play only a negligible role in the deexcitation

ISSN:0003-3804    

DOI:10.1002/andp.19925040304

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe eigenvalue problem for arbitrary linear combinationskα + μα†of a boson annihilation operator α and a boson creation operator α†is solved. It is shown that these operators possess nondegenerate eigenstates to arbitrary complex eigenvalues. The expansion of these eigenstates into the basic set of number states |n>, (n= 0, 1, 2, …), is found. The eigenstates are normalizable and are therefore states of a Hilbert space for | ζ |<1 with ζ  μ/kand represent in this case squeezed coherent states of minimal uncertainty product. They can be considered as states of a rigged Hilbert space for | ζ | ⩾ 1. A completeness relation for these states is derived that generalizes the completeness relation for the coherent states | α 〉. Furthermore, it is shown that there exists a dual orthogonality in the entire set of these states and a connected dual completeness of the eigenstates on widely arbitrary paths over the complex plane of eigenvalues. This duality goes over into a selfduality of the eigenstates of the hermitian operatorskα +k* α†to real eigenvalues. The usually as nonexistent considered eigenstates of the boson creation operator α†are obtained by a limiting procedure. They belong to the most singular case among the considered general class of eigenstate

ISSN:0003-3804    

DOI:10.1002/andp.19925040305

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

Dynamics of an Array of two Tunnel Junctions with Ultrasmall Capacitances and Superconducting ElectrodesThe dynamics of a series array of two voltage‐biased SET junctions with superconducting electrodes is investigated in the frame of a master equation formalism. Explicit expressions for the number of electrons on the central electrode and the electric current are given in the zero temperature case. Situations without current are analyzed in detail and using current‐voltage characteristics, special properties of the system in the stationary regime are discus

ISSN:0003-3804    

DOI:10.1002/andp.19925040306

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractWe present a calculation of the electronic Raman cross section for the scattering of light across the energy gap of an antiferromagnetic insulator. The antiferromagnet is described in terms of a spin density wave state for the Hubbard model at half filling. We consider the coupling of the light to the current density and the inverse mass tensor on equal footing. A comparison of the cross section for different scattering geometries is given.

ISSN:0003-3804    

DOI:10.1002/andp.19925040307

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractSuperconductivity of Heavy‐Fermions, with an emphasis on hexagonal UPt3, is investigated microscopically on the basis of the LNCA‐approximation for strongly correlated electrons in a Kondo lattice and of Eliashberg theory for anisotropic singlet and triplet superconducting order. The effective interaction kernel incorporates exchange of spin fluctuations carried by strongly renormalized particle‐hole excitations as well as exchange of phonons generated by the breathing mechanism. Particular care is taken to include realistic anisotropies in band structure and couplings and to expand interaction kernel and order parameter in appropriate Fermi surface harmonics. Separate interactions and corresponding gap equations are used for pseudo‐spin‐singlet and ‐triplet channel, with a restriction to the case of weak spin‐orbit coupling. Our main results include a detailed study of phonon‐ and spin‐fluctuation mechanisms as a possible source for superconductivity and, in combination, their mutual influence and competition. Furthermore, the questions regarding singlet or triplet order, conventional or unconventional symmetry, order parameter zeros and phase transitions between different superconducting states are addressed. We propose a possible scenario of Heavy‐Fermio

ISSN:0003-3804    

DOI:10.1002/andp.19925040308

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

摘要:

AbstractThe Zakharov‐Kuznetsov equation has been used to describe ion‐acoustic wave propagation in a strong magnetic plasma. An initial‐value problem has been solved for this equation on the basis of a numerical method that uses the fast Fourier transform technique for calculating space derivatives and a fourth order Runge‐Kutta method for the time scheme. Numerical simulations have shown that the disturbed flat solitary waves can break up into spheric

ISSN:0003-3804    

DOI:10.1002/andp.19925040309

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY

ISSN:0003-3804    

DOI:10.1002/andp.19925040301

出版商:WILEY‐VCH Verlag    

年代:1992

数据来源: WILEY