摘要:

AbstractResults of light scattering and small angle neutron scattering experiments with a 2‐butoxyethanol (2‐C4E1)/D2O mixture of critical composition (stoichiometric mole fraction of 2‐C4E1x c0= 0.0598; critical temperatureTc(visual) = 42.714 °C) are reported. They are carried out with the aim to find out whether the temperature dependence of the correlation length ξ characterizing the extension of concentration fluctuations nearTcis different from that characterizing the size of aggregates of the 2‐C4E1molecules which appear to exist at temperatures away fromTc. The experiments show that the temperature dependence of ξ nearTcis the same as that away fromTcwithin the uncertainty of the measurements. – As a by‐product of this study, neutron scattering data were collected corresponding to a wide range of values of the scaling variablex(3

ISSN:0003-3804    

DOI:10.1002/andp.19945060102

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractThe electromagnetic surface impedance of single crystal high‐Tcsuperconductors has been examined within the framework of the two‐fluid model and the hypothesis that thee mfield modulates the partial concentrations of both normal and condensate fluids. A comparison with experimental data is repor

ISSN:0003-3804    

DOI:10.1002/andp.19945060103

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractAmplitude and phase of high frequency surface acoustic wave (SAW) fields are investigated by a novel scanning tunneling microscopy technique. The gap voltage is modulated at a slightly detuned high frequency. Due to the nonlinearity of the tunneling process a frequency mixing appears. For scanned areas with dimensions much smaller than the wavelength of the SAW a remarkable local variation of amplitude and phase of the tunneling current at the difference frequency is observed. Depending on the local morphology different components of the particle displacement vector are detected. Model calculations of amplitude and phase images are presented for a real topography.

ISSN:0003-3804    

DOI:10.1002/andp.19945060104

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractInformation about the transport time of electrons through a quasi one‐dimensional sample is obtained by calculating the energy auto‐correlation function of the conductance. Depending on the length of the sample and its coupling to the external device (here modelled by perfectly conducting leads), the transport time undergoes a smooth crossover between two different limiting regimes. In the case of long samples and good coupling it coincides with the diffusion time. In the opposite limit of short and weakly coupled systems, however, the transport time is given by the reciprocal of the quantum mechanical decay width into the leads. The transition between both regimes is discussed in terms of a few model independent conce

ISSN:0003-3804    

DOI:10.1002/andp.19945060105

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractUsing linear response theory we show that, in a quasi‐stationary state, the local multiprobe conductance of a mesoscopic system of non‐interacting electrons with a time reversal invariant Hamiltonian does not depend on the local shape of the driving self‐consistent potential and thus is entirely determined by the asymptotic values of the potential in the leads. In the ballistic limit, the local conductance in the lateral direction exhibits oscillations depending on the occupation of channels. Scattering by a point impurity leads to softening of the quantized global conductance steps. In addition to that for an attractive scattering potential, a dip occurs in each plateau regime the shape of which is calculated for different values of the potential strength. We also investigate the local conductance for both a point scatterer and a finite scattering r

ISSN:0003-3804    

DOI:10.1002/andp.19945060106

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

摘要:

AbstractDirac's equation with gravity for a noninertial observer is derived using local coordinate methods. Calculations for the equation are carried out to second order in the local coordinates. For easy application to interference experiments, the Schrödinger form of the Dirac equation with a well defined Hamiltonian in the local coordinates is presented. The presence of gravitational weighting factors in the scalar product lead to hermitian and antihermitian sectors for the Hamiltonian. The antihermitian part depends directly on the curvature and vanishes for zero curvature. The hermitian part which is important for the determination of phases is studied in detail and the nonrelativistic case is obtained by the application of three successive Foldy‐Wouthuysen transformations. The results also give local currents and interactions which have pure inertial, pure gravity and mixed sectors. The pure inertial terms are the ones obtained by Hehl and Ni. The pure gravity and mixed sectors have contributions which are electric, magnetic and double magnetic in character. The focus is on the curvature contributions. Some are well within reach of the anticipated accuracy of atomic interferometers currently under consideration and other terms may follow if improvements can be ma

ISSN:0003-3804    

DOI:10.1002/andp.19945060107

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY

ISSN:0003-3804    

DOI:10.1002/andp.19945060101

出版商:WILEY‐VCH Verlag    

年代:1994

数据来源: WILEY