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33.
Yu. S. Boyarskaya J. Schreiber D. Z. Grabko M. P. Dyntu B. M. Pushkash 《Crystal Research and Technology》1981,16(8):965-970
The (111) plane of MgO single crystals was deformed by a concentrated load. It was observed that the number of rows of a cathodoluminescence rosette is a factor of two lower than that for the etch pit one. The explanation of this phenomenon is given. The polarity of plastic deformation was revealed using both an etch pit technique and cathodoluminescence method. It is shown that deformation causes a change of the cathodoluminescence spectra. The spectra, obtained from crystal deformed by indentation and from compressed crystal, are similar. 相似文献
34.
S. Thiem M. Schreiber 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(4):415-421
From the quantum mechanical point of view, the electronic characteristics of
quasicrystals are determined by the nature of their eigenstates. A practicable way to
obtain information about the properties of these wave functions is studying the scaling
behavior of the generalized inverse participation numbers Zq ~ N - Dq (q - 1)Z_q \sim N - ^{D_q (q - 1)} with the system size N. In particular, we investigate
d-dimensional quasiperiodic models based on different metallic-mean
quasiperiodic sequences. We obtain the eigenstates of the one-dimensional metallic-mean
chains by numerical calculations for a tight-binding model. Higher dimensional solutions
of the associated generalized labyrinth tiling are then constructed by a product approach
from the one-dimensional solutions. Numerical results suggest that the relation D
q
dd = dD
q
1d holds for these models. Using the product structure of the labyrinth tiling we prove that
this relation is always satisfied for the silver-mean model and that the scaling exponents
approach this relation for large system sizes also for the other metallic-mean
systems. 相似文献
35.
36.
F. Schreiber M. Hoffmann O. von Geisau J. Pelzl 《Applied Physics A: Materials Science & Processing》1993,57(6):545-551
The conventional and photothermally modulated (PM) ferromagnetic resonance (FMR) of magnetostatic modes (MSM) in yttrium iron garnet (YIG) films have been investigated as a function of temperature. Approaching the ferrimagnetic transition at T
c=560 K a strong enhancement of the PM-FMR signal amplitude is observed which is accompanied by a change of the signal shape. The observations are discussed in the framework of a model that takes into account the temperature derivatives of those quantities that contribute to the high-frequency susceptibility. At temperatures still below T
c a paramagnetic line emerges. The MSM disappear in a state of finite magnetization which is explained on the basis of damping of the MSM being important in the vicinity of the magnetic phase transition. Additionally, frequency and power dependent measurements are presented and the imaging ability of PM-FMR is demonstrated. 相似文献
37.
38.
Urs Schreiber 《Communications in Mathematical Physics》2009,291(2):357-401
There are essentially two different approaches to the axiomatization of quantum field theory (QFT): algebraic QFT, going back to Haag and Kastler, and functorial QFT, going back to Atiyah and Segal. More recently, based on ideas by Baez and Dolan, the latter is being refined to “extended” functorial QFT by Freed, Hopkins, Lurie and others. The first approach uses local nets of operator algebras which assign to each patch an algebra “of observables”, the latter uses n-functors which assign to each patch a “propagator of states”.In this note we present an observation about how these two axiom systems are naturally related: we demonstrate under mild assumptions that every 2-dimensional extended Minkowskian QFT 2-functor (“parallel surface transport”) naturally yields a local net, whose locality derives from the 2-categorical exchange law, and which is covariant if the 2-functor is equivariant. This is obtained by postcomposing the propagation 2-functor with an operation that mimics the passage from the Schrödinger picture to the Heisenberg picture in quantum mechanics. The argument has a straightforward generalization to general Lorentzian structure, bare lightcone structure and higher dimensions. It does not, however, by itself imply anything about the existence of a vacuum state or about positive energy representations. 相似文献
39.
G. Baszenski U. Schreiber G. Tasche 《Numerical Functional Analysis & Optimization》2013,34(1-2):25-46
In this paper we consider the numerical stability of fast algorithms for discrete cosine transform (DCT) of type III and II, respectively. We show that various fast DCTs can possess a very different behaviour of numerical stability. By matrix factorizations we find that a complex fast DCT which is based mainly on a fast Fouier transform has a better numerical stability than a real fast DCT despite its larger arithmetical complexity. Numerical tests illustrate our theoretical results. 相似文献
40.
We investigate the relation between the optical properties and the average molecular tilt angle for blends of pentacene and perfluoropentacene, which can be considered as a prototypical donor–acceptor complex. Combining near‐edge X‐ray absorption fine‐structure spectroscopy and optical spectroscopy we study thin films of these compounds prepared at three different substrate temperatures Tsub. For Tsub =180 K we observe a larger average tilt angle than for blends prepared at higher substrate temperatures. This orientational change has significant impact on the uniaxial anisotropic optical properties of the mixed films which we measure post growth as well as in real‐time during growth. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献