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1.
We report the results of theoretical investigations of tunneling current noise spectra in a wide range of applied bias voltage.
Localized states of individual impurity atoms play an important role in tunneling current noise formation. It was found that
switching “on” and “off” of Coulomb interaction of conduction electrons with two charged localized states results in power
law singularity of low-frequency tunneling current noise spectrum (1/f
α) and also results on high frequency component of tunneling current spectra (singular peaks appear).
The article is published in the original. 相似文献
2.
Angular dependences of the magnetization hysteresis loops have been studied at T=77 K on YBCO single crystals exhibiting the peak effect. The peak effect is shown to be related to the pinning of longitudinal
vortices along the c axis at twin boundary-type ordered defects. The behavior of the peak effect at intermediate angles is explained by anisotropic
magnetic field penetration into quasi-two-dimensional superconductors. In thin crystals with a dilute ordered-defect structure
this can result in an enhanced peak effect due to formation of a vortex kink structure and to “internal” pinning of transverse
vortex segments at Cu-O sheets.
Fiz. Tverd. Tela (St. Petersburg) 39, 425–431 (March 1997) 相似文献
3.
R. V. Gainutdinov T. R. Volk O. A. Lysova I. I. Razgonov A. L. Tolstikhina L. I. Ivleva 《Applied physics. B, Lasers and optics》2009,95(3):505-512
The recording of microdomains and regular 1D- (linear) and 2D- (square) domain arrays was performed in SBN crystals by means
of applying low (within 10 V) DC voltages to an AFM tip. The ferroelectric phenomena under AFM-tip fields (P–E hysteresis loops, the domain dynamics, etc.) agree qualitatively with the polarization processes observed at the macroscopic
level and reveal peculiarities obviously related to the relaxor origin of SBN crystals. Particularly, the domain formation
and the domain-wall lateral motion occur under fields much lower than E
c
, which founds no explanation in terms of the model approach to the ferroelectric switching. The formation of linear and square
domains results from overlapping closely spaced individual domains. For the first time a drastic dependence of the temporal
stability on the domain topology was found. Namely, at identical exposure conditions of recording, the lifetimes of individual
domains, domain lines, and domain squares (“chessboards”) are, respectively, several minutes, tens of hours, and no less than
a month. 相似文献
4.
J.-P. Rivera 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,71(3):299-313
Whereas materials with intrinsic magnetoelectric (ME) effects have not yet
made inroads in technology, the measurement of their tensor characteristics
has become a precious tool for magnetic point group determination.
Therefore, it is worthwhile to consider different measurement techniques. In
particular techniques for determining the linear and bilinear ME effects
will be discussed, essentially the quasi-static and dynamic magnetic
field-induced methods will be evaluated. The measurement and application of
ME “butterfly" loops for determining (weak) ferromagnetism and internal bias
fields will be described. For the bilinear ME effect (with invariant EHH) a
particularly sensitive measurement method with amplification effect will be
highlighted, permitting, e.g., to detect subtle magnetic phase transitions.
At least for the linear ME effect, we will stress that in the future only a
dimensionless quantity should be used which is valid in all systems of
units. Finally, the linear ME effect of TbPO4 crystals is reexamined
because in a former publication it was not clear which system of units was
effectively used (“rationalized” or “not rationalized” Gaussian system
of units). Effectively, this crystal has the largest linear ME effect known.
At T = 1.50 K, in SI units: α
xy or α
yx = 730 ps/m, i.e., 0.220 in
“not rationalized” Gaussian system of units. 相似文献
5.
F. Šrobár 《Czechoslovak Journal of Physics》1999,49(5):783-789
A modified version of the signal flow graphs method can be applied to reveal the topological structure of physical models
describing the operation of optoelectronic devices based on heterostructures comprising AIIIBV semiconductor compounds. In particular, this kind of analysis is apt to reveal the presence of closed paths (feedback loops)
in the causal make-up of the phenomena underlying function of the devices. The analytical apparatus associated with the diagrams
affords a new formulation of criteria for the occurrence of such physical conditions as the bistability or the threshold behaviour.
The approach is illustrated on the instances of injection semiconductor laser, nonlinear Fabry-Perot resonator, self-electro-optic
effect device and semiconductor laser optical amplifier.
Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998
Support of the Grant Agency of the Czech Republic (project No. 102/99/0341) is gratefully acknowledged. 相似文献
6.
We analyse, within the “flavoured” leptogenesis scenario of baryon asymmetry generation, the interplay of “low energy” CP-violation,
originating from the PMNS neutrino mixing matrix U, and “high energy” CP-violation, which can be present in the matrix of neutrino Yukawa couplings, λ, and can manifest itself only in “high” energy scale processes. The type I see-saw model with three heavy right-handed Majorana
neutrinos having a hierarchical spectrum is considered. The “orthogonal” parameterisation of the matrix of neutrino Yukawa
couplings, which involves a complex orthogonal matrix R, is employed. In this approach the matrix R is the source of “high energy” CP-violation. Results for normal hierarchical (NH) and inverted hierarchical (IH) light neutrino
mass spectrum are derived in the case of decoupling of the heaviest right-handed Majorana neutrino. It is shown that taking
into account the contribution to Y
B
due to the CP-violating phases in the neutrino mixing matrix U can change drastically the predictions for Y
B
, obtained assuming that only “high energy” CP-violation from the R-matrix is operative in leptogenesis. In the case of the IH spectrum, in particular, there exist significant regions in the
corresponding parameter space where the purely “high energy” contribution in Y
B
plays a subdominant role in the production of baryon asymmetry compatible with the observations.
Also at Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria. 相似文献
7.
8.
Shiyong Liu Jingsong Huang Zhiyuan Xie Baijun Chen Yue Wang Jiacong Shen 《Czechoslovak Journal of Physics》1999,49(5):849-857
Several organic electroluminescent devices have been fabricated by multi-source high vacuum deposition system. For high brightness
organic electroluminescent device, the maximum brightness is over 40000 cd/m2. For quantum well structures, quantum size effect has been investigated and the high light emission efficiencies of the devices
have been obtained. White-light emission from organic multi-quantum well structures is proposed at first. Brightness of the
white-light MQW devices reaches 4000 cd/m2 at 17 V.
Presented at the 1st Czech-Chinese Workshop “Advanced Materials for Optoelectronics”, Prague, Czech Republic, June 13–17,
1998.
The research is supported by the National “863” Project of China [No. 863-307-05-05(02)] and by the National Natural Science
Foundation of China [No. 69637010]. 相似文献
9.
Zhuanlan Sun Xiaoqing Zhang Zhongfu Xia Xunlin Qiu Werner Wirges Reimund Gerhard Changchun Zeng Chuck Zhang Ben Wang 《Applied Physics A: Materials Science & Processing》2011,105(1):197-205
Laminated polymer-film systems with well-defined void structures were prepared from fluoroethylenepropylene (FEP) and polytetrafluoroethylene
(PTFE) layers. First the PTFE films were patterned and then fusion-bonded with the FEP films. The laminates were subjected
to either corona or contact charging in order to obtain the desired piezoelectricity. The build-up of the “macro-dipoles”
in the laminated films was studied by recording the electric hysteresis loops. The resulting electro-mechanical properties
were investigated by means of dielectric resonance spectroscopy (DRS) and direct measurements of the stress-strain relationship.
Moreover, the thermal stability of the piezoelectric d
33 coefficient was investigated at elevated temperatures and via thermally stimulated discharge (TSD) current measurements in
short circuit. For 150 μm thick laminated films, consisting of one 25 μm thick PTFE layer, two 12.5 μm thick FEP layers, and
a void of 100 μm height, the critical voltage necessary for the build-up of the “macro-dipoles” in the inner voids was approximately
1400 V, which agrees with the value calculated from the Paschen Law. A quasi-static piezoelectric d
33 coefficient up to 300 pC/N was observed after corona charging. The mechanical properties of the film systems are highly anisotropic.
At room temperature, the Young’s moduli of the laminated film system are around 0.37 MPa in the thickness direction and 274 MPa
in the lateral direction, respectively. Using these values, the theoretical shape anisotropy ratio of the void was calculated,
which agrees well with experimental observation. Compared with films that do not exhibit structural regularity, the laminates
showed improved thermal stability of the d
33 coefficients. The thermal stability of d
33 can be further improved by pre-aging. E.g., the reduction of the d
33 value in the sample pre-aged at 150°C for 5 h was less than 5% after annealing for 30 h at a temperature of 90°C. 相似文献
10.
F. Benvenuti G. Bergamasco G. Zini 《Applied Physics A: Materials Science & Processing》1973,2(5):237-240
When an elastic shear stress and a cyclical magnetic field, parallel to each other, are applied in the plane of a ferromagnetic
sheet, magnetization changes perpendicular to the field are induced in the sample. “Transverse” hysteresis loops, i.e. transverse
magnetization plotted as a function of the longitudinal field, were studied in various materials. The characteristic shape
of the loop and the differences in sign and magnitude of the “transverse” magnetization have been qualitatively explained
in terms of magnetic domain theory.
Work supported by G.N.S.M. (CNR). 相似文献
11.
We study the pinning-depinning phenomenon of a contact line on a solid surface decorated by a random array of nanometric structures.
For this purpose, we have investigated the contact angle hysteresis behaviour of six different wetting and non-wetting fluids
with surface tensions varying from 25 to 72mN m^-1. For low values of the areal density of defects φd, the hysteresis H increases linearly with φd indicating that “individual” defects pin the contact line. Then, from a given value of φd, the hysteresis H becomes to decrease with increasing φd, indicating a new kind of collective depinning. These two regimes were observed for all fluids used. In both cases, our experimental
results are compared with the theoretical predictions for contact angle hysteresis induced by single or multiple topographical
defects. We ascribe the decrease of H to the formation of cavities along the wetting front. 相似文献
12.
Anastasios Mallios 《International Journal of Theoretical Physics》2006,45(8):1552-1588
“Geometry,” in the sense of the classical differential geometry of smooth manifolds (CDG), is put under scrutiny from the point of view of Abstract Differential Geometry (ADG). We explore potential physical implications of viewing things under the light of ADG, especially matters concerning the “gauge theories” of modern physics, when the latter are viewed (as they are actually regarded currently) as “physical theories of a geometrical character.” Thence, “physical geometry,” in connection with physical laws and the associated with them, within the background spacetime manifoldless context of ADG, “differential” equations, are also being discussed. 相似文献
13.
Fabio Gavarini 《Czechoslovak Journal of Physics》2001,51(12):1330-1335
The “quantum duality principle” states that a quantisation of a Lie bialgebra provides also a quantisation of the dual formal
Poisson group and, conversely, a quantisation of a formal Poisson group yields a quantisation of the dual Lie bialgebra as
well. We extend this to a much more general result: namely, for any principal ideal domainR and for each primepεR we establish an “inner” Galois’ correspondence on the categoryHA of torsionless Hopf algebras overR, using two functors (fromHA to itself) such that the image of the first and the second is the full subcategory of those Hopf algebras which are commutative
and cocommutative, modulop, respectively (i.e., they are“quantum function algebras” (=QFA) and“quantum universal enveloping algebras” (=QUEA), atp, respectively). In particular we provide a machine to get two quantum groups — a QFA and a QUEA — out of any Hopf algebraH over a fieldk: apply the functors tok[ν] ⊗k H forp=ν.
A relevant example occurring in quantum electro-dynamics is studied in some detail.
Presented at the 10th International Colloquium on Quantum Groups: “Quantum Groups and Integrable Systems”, Prague, 21–23 June
2001 相似文献
14.
Heinrich Saller 《International Journal of Theoretical Physics》2006,45(11):2150-2180
Special relativity, the symmetry breakdown in the electroweak standard model, and the dichotomy of the spacetime related transformations with the Lorentz group, on the one side, and the chargelike transformations with the hypercharge and isospin group, on the other side, are discussed under the common concept of “relativity.” A relativity is defined by classes G/H of “little” group in a “general” group of operations. Relativities are representable as linear transformations that are considered for five physically relevant examples.Finite Dimensional Relativity Representations 相似文献
15.
Moisture invasion into memory devices can result in data loss and malfunctions in write/erase switching. Deteriorated uniformity and retention characteristics, and distorted switching hysteresis loops, are observed in moisture-attacked Pt-dispersed SiO2 nanometallic thin-film devices, and can be effectively prevented by coating the device with a nanoscale Al2O3 barrier layer grown by an atomic layer deposition method. The moisture-attacked devices exhibit evidence of cumulating ion current and ion potential with repeated switching. In contrast, a capped device with an extremely uniform and reproducible resistive switching behavior features a completely symmetric current–voltage curve expected for a purely electronic device. 相似文献
16.
H. L. Kwok 《Applied physics. B, Lasers and optics》2009,94(2):279-282
Organic field-effect transistors (OFETs) have received significant attention recently because of the potential application
in low-cost flexible electronics. The physics behind their operation are relatively complex and require careful consideration
particularly with respect to the effect of charge trapping at the insulator–semiconductor interface and field effect in a
region with a thickness of a few molecular layers. Recent studies have shown that the so-called “onset” voltage (V
onset) in the rubrene OFET can vary significantly depending on past illumination and bias history. It is therefore important to
define the role of the interface trap states in more concrete terms and show how they may affect device performance. In this
work, we propose an equivalent-circuit model for the OFET to include mechanism(s) linked to trapping. This includes the existence
of a light-sensitive “resistor” controlling charge flow into/out of the interface trap states. Based on the proposed equivalent-circuit
model, an analytical expression of V
onset is derived showing how it can depend on gate bias and illumination. Using data from the literature, we analyzed the I–V characteristics of a rubrene OFET after pulsed illumination and a tetracene OFET during steady-state illumination. 相似文献
17.
Frederick W. Kantor 《International Journal of Theoretical Physics》1982,21(6-7):525-535
This article is concerned with the conceptual background of information mechanics (IM) and some of the consequences of axiomatization
of IM, and touches on some examples as to instances in which IM might seem to have offered, within a single conceptual picture,
interesting approaches to some questions which have variously been regarded as quite different. In IM, representation of information
in physical systems is treated as a conceptual, computation, and design tool. Some examples touched on are an IM approximate
relation among,h, c, m
e, G, and ∼α; particle masses and mass-charge relation; cosmological red shift without assuming that distant light sources are rapidly
receding; gravity; and knowability of prediction. IM is then used as a tool for looking into making information processing
“hardware” out of “software”, with information representations formed within extended region(s) of nearly homogeneous “medium(s)”.
All or part of this material may be or become the subject of U.S. or foreign patents pending or issued. Inclusion of any material
herein shall not be construed as implying any license under any patent. 相似文献
18.
A “capacitor” model of the hysteresis is developed using the self-consistent calculation of the tunneling current in a w-GaN/AlGaN(0001) double-barrier structure. In the framework of this model, the current jumps and changes in the potential
and the electric field in the structure upon transition from one branch of the current loop to the other branch are considered
a result of the recharging of two joined capacitors with the plates located at the positions of the extrema of variations
in the electron density in the regions of the emitter, the quantum well, and the collector. It is demonstrated that, when
the external and internal fields in the quantum well compensate for each other, the tunneling current is sharply and irreducibly
switched to the characteristics of the other resonance and forms a wide hysteresis loop so that, in the branches of this loop,
the charge is redistributed between the quantum well and the collector. If the fields coincide with each other, there arises
a narrow “singleresonance” hysteresis loop, which is accompanied by the transfer of the electron charge from the emitter to
the collector. The developed model leads to agreement with the results of the self-consistent calculations and provides an
illustrative interpretation of the complex electron tunneling processes.
Original Russian Text ? A.N. Razzhuvalov, S.N. Grinyaev, 2009, published in Fizika Tverdogo Tela, 2009, Vol. 51, No. 1, pp.
168–177. 相似文献
19.
Y. S. Akishev G. Aponin A. Balakirev M. Grushin V. Karalnik A. Petryakov N. Trushkin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,61(2):421-429
The results of an experimental study on a spatial-time behavior of
microdischarges (MDs) in steady-state dielectric barrier discharge (DBD) are
presented. MDs of DBD have a spatial “memory”, i.e. every subsequent MD
appears exactly at the same place that was occupied by the preceding MD. In
most cases each MD appears at its fixed place only once by every half-period (HP). Spatial “memory” is derived from slow
recombination of plasma in the MDs channels for a period between two
neighbor HPs. In steady-state DBD each plasma column was formed only
one-time due to local avalanche-streamer breakdown in the very first
(initial) gas gap breakdown under inception voltage U*U^*. After that
DBD is sustained under voltage lower than U*U^*. For the
plane-to-plane DBD having the restricted electrode area there is a critical
voltage U
1: DBD is in a steady-state if U
>
U
1 but the DBD decays
slowly at voltages below U
1. The decay takes many HPs and occurs due to
decreasing the number of MDs inside the gap because of their Brownian motion
from central region to the outside of the discharge area. In steady-state
DBD there is no correlation between an appearance of alone MD and phase of
the applied voltage – each MD has a great scatter in its appearance at the
HP. This scatter is attributed to the dispersion in a threshold voltage for
local surface breakdowns around the MD base. So, in steady-state DBD the MD
volume plasma is responsible for an existence of spatial “memory” (i.e.
where the MD appears) but the surface charge distribution around MD
is responsible for MD time dispersion (i.e. when the MD appears). 相似文献
20.
Joseph Ben Geloun Vincent Rivasseau 《The European Physical Journal C - Particles and Fields》2008,58(1):115-122
The β-functions of O(N) and U(N) invariant Grosse–Wulkenhaar models are computed at one loop using the matrix basis. In particular, for “parallel interactions”,
the model is proved to be asymptotically free in the UV limit for N>1, and it has a triviality problem or Landau ghost for N<1. The vanishing β-function is recovered solely at N=1. We discuss various possible consequences of these results.
Work supported by the ANR Program “GENOPHY” and by the Daniel Iagolnitzer Foundation, France. 相似文献