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1.
《Superlattices and Microstructures》1994,16(2):187
We present the anomalous magnetotransport observed in a narrow high mobility Hall device; both the peaks and minima in the Shubnikov de Haas oscillations of the longitudinal resistance appear in the quantized plateau region of the Hall resistance. We interpret this feature as a consequence of an inhomogeneous distribution of two dimensional electron gas and provide a quantitative view with a model based on the edge current picture. 相似文献
2.
N. Morawicz K.W.J. Barnham A. Briggs S. Najda J.-C. Portal J.J. Harris C.T. Foxon 《Superlattices and Microstructures》1990,8(4)
We report on experiments performed on a high quality, high carrier concentration
heterostructure at a range of hydrostatic pressures. At a pressure of 1 bar a clear xx minimum and Hall plateau were observed associated with a
fractional state while no such structure was observed for the
fractional state. At increasing pressure however structure in the resistivity components xx and xy for the
state became increasingly pronounced. As the disorder in the sample and the measured activation energy for the
state remained relatively unchanged with increasing pressure we speculate that the enhancement of the
state with increasing pressure is due to an increase in the energy gap for this state. 相似文献
3.
Luis Miguel Sanchez-Brea Francisco Jose Torcal-Milla Eusebio Bernabeu 《Optics Communications》2007,278(1):23-27
Metallic gratings can be found in applications such as optical metrology. Due to their fabrication process, the surface presents a certain roughness. In this work, the effect of roughness on Talbot effect has been analyzed when the grating is illuminated with a Gaussian beam. A model based on Fresnel regime is used in order to determine the intensity distribution in the near field. Contrast of the self-images is obtained and it is found that it decreases in terms of the distance between the grating and the observation plane. When the autocorrelation function of roughness presents a Gaussian behaviour, the diffracted beams are still Gaussian although some of their properties change. For example, the width of the diffracted beams increases with respect to the case of the standard chrome on glass gratings. On the other hand, the power of each diffracted beam is independent on the roughness properties of the surface. 相似文献
4.
P. S. Alekseev 《JETP Letters》2010,92(12):788-792
Electron tunneling in a semiconductor heterostructure with a barrier in a weak magnetic field applied parallel to the barrier
interfaces is analyzed theoretically. A novel mechanism of the Hall effect in this structure is suggested. It is shown that
the Hall current near the sufficiently wide barrier is determined by the orbital effect of the magnetic field on the electron
motion under the barrier, rather than by the electron {ie778-1}-drift and scattering in the conductive regions lying to the
left and to the right of the barrier. 相似文献
5.
6.
The spin Hall effect—the excitation of a spin flux by an electric current normal to it—is considered in a paramagnetic sample in disregard of the spin-orbit coupling in the classical Hall effect case, when the Pauli spin polarization is induced by the magnetic field H 0 normal to the electric current. 相似文献
7.
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
8.
É. M. Épshtein 《Physics of the Solid State》2002,44(7):1327-1329
The planar Hall effect in a ferromagnetic conductor is considered within a simple two-liquid hydro-dynamic model. It is shown that, even in the simple case of an isotropic Fermi surface in the absence of thermal spread, the magnitude of the Hall effect is comparable to that in semiconductors because of the presence of two groups of conduction electrons with their spins parallel and perpendicular to the quantization axis, respectively. In addition to the planar Hall field, a spin flux parallel to this field arises, with the consequence that the extent of spin polarization of the conduction electrons varies along the Hall field direction (planar spin Hall effect). 相似文献
9.
The Talbot effect under illumination of double femtosecond laser pulses has been reported. Spectrums of double femtosecond laser pulses with phase differences are quite different from that of one single femtosecond laser pulse. Therefore, the Talbot images of the double femtosecond laser pulses with phase differences are different from that of one single femtosecond laser pulse. Specifically, for the phase difference corresponding to π, the Talbot image shows the largest difference from that of one single pulse. Experimental results are in good agreement with the theoretical analysis. The behaviors of Talbot images under double femtosecond laser pulses illumination cannot be obtained under one femtosecond laser pulse, monochromatic or polychromatic light illumination. Therefore, it is a new interesting optical phenomenon for the Talbot effect which should have potential applications. 相似文献
10.
A remarkable analogy is established between the well-known spin Hall effect and the polarization dependence of Rayleigh scattering of light in microcavities. This dependence results from the strong spin effect in elastic scattering of exciton polaritons: if the initial polariton state has a zero spin and is characterized by some linear polarization, the scattered polaritons become strongly spin polarized. The polarization in the scattered state can be positive or negative dependent on the orientation of the linear polarization of the initial state and on the direction of scattering. Very surprisingly, spin polarizations of the polaritons scattered clockwise and anticlockwise have different signs. The optical spin Hall effect is possible due to strong longitudinal-transverse splitting and finite lifetime of exciton polaritons in microcavities. 相似文献
11.
J.M. DonallyM. Cutler 《Journal of Physics and Chemistry of Solids》1972,33(5):1017-1022
The proper interpretation of the Hall coefficient RH of liquid semiconductors is still an unsolved problem, and it is a particularly interesting one in view of the frequently observed discrepancy in sign with the Seebeck coefficient. We present some new data which include measurements of the Hall mobility μH in liquid thallium-tellurium through the composition range where the Seebeck coefficient S changes sign, and in the range where S is negative. An abrupt change in magnitude of μH occurs at the intrinsic composition (Tl2Te, where S changes sign), and μH is observed to have an appreciable dependence on temperature only at this composition. This is consistent with transport by carriers in two bands. μH is lower on the Tl-rich side of Tl2Te, and the formula nH = 1/RHe yields a value for nH which is ten times larger than the electron concentration inferred from the composition, assuming that electrons are derived from the Tl in excess of Tl2Te. We review the various suggested interpretations of the Hall effect in liquid semiconductors from several points of view, and conclude that the conventional formula n = ± 1/RHe is unreliable for inferring either the sign or concentration of the carriers. 相似文献
12.
《Journal of Physics and Chemistry of Solids》1986,47(6):581-585
Analytical investigation is made of the electron-hole diffusion in compensated media like semimetals, which takes place under crossed electric and magnetic fields. It is shown that the diffusion of carriers causes a transverse field effect different to the usual Hall one, if the conducting medium is bounded. The transverse voltage due to this effect increases almost linearly with the magnetic field (H), and changes its sign according to the polarity of H. This voltage is observable even for bulk specimens for which the usual size effect is negligible, but its appearance is easily masked in the presence of impurities. A detailed discussion is made for bismuth, considering a non-parabolic model for the electron Fermi surface. The transverse voltage is found to be very sensitive to the surface recombination velocity of the carriers as well as to the impurity concentration. 相似文献
13.
We show that in the conditions where the quantized Hall effect is observed, capacitance oscillations of the junction should be present. A comparison between the plateaux of Hall resistance and the amplitude of the capacitance oscillations gives the amount of localized states in the two-dimensional electron gas. 相似文献
14.
Experimental results of the Talbot effect of an amplitude grating under femtosecond laser illumination are reported. Compared with Talbot image under continuous wave (CW) illumination, Talbot images under femtosecond laser illumination are different due to the wide spectral bandwidth and the Talbot images are more distorted at longer Talbot distances. The spectrums and the pulsewidths of femtosecond laser pulses are measured with the frequency-resolved optical gating (FROG) apparatus. Experimental results are in good agreement with the theoretical analysis. 相似文献
15.
The Talbot effect of a high-density grating under femtosecond laser illumination is analyzed with rigorous electromagnetic theory which is based on the Fourier decomposition and the rigorous coupled-wave analysis (RCWA). Numerical simulations show that the contrast of the Talbot images steadily decreases as the transmitted femtosecond laser pulses propagate forward and with wider spectrum width of the femtosecond laser pulses. The Talbot images of high-density gratings have much higher sensitivity of the spectrum widths of the incident laser pulses than those of the traditional low-density gratings. In experiments, the spectrums and the pulse widths of the incident pulses are measured with a frequency-resolved optical grating (FROG) apparatus. The Talbot images are detected by using a Talbot scanning near-field optical microscopy (Talbot-SNOM) technique, which are in coincidence with the numerical simulations. This effect should be useful for developing new femtosecond laser techniques and devices. 相似文献
16.
The effect of a transverse magnetic field on a one-dimensional metallic current carrying conductor is considered. The field produces a transverse electric polarization which is wavevector dependent, and which causes a transverse magnetoelectric field. The magnitude of the effect is estimated for typical one dimensional conductors. 相似文献
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18.
A. L. Parakhonskiĭ M. V. Lebedev I. V. Kukushkin Yu. Smet K. von Klitzing 《Physics of the Solid State》2007,49(5):976-983
Giant fluctuations in the 2D-electron recombination radiation were studied in structures with a single or double GaAs quantum well under quantum Hall effect conditions. It is established that, if these conditions are exactly satisfied, the amplitude of the 2D-electron photoluminescence (PL) intensity is several orders of magnitude higher than the noise level, with the noise having a normal (Poisson) distribution. The fluctuations in the PL line intensity are accompanied by a jumpwise change in the line positions. Analogous jumps were also observed in the spectra of inelastic light scattering by 2D electrons in structures with a single GaAs quantum well. The fluctuation processes are correlated over macroscopic distances. The characteristic correlation length is 1–2 mm. The spectral density of giant fluctuations was found to exhibit narrow peaks. The ratios of the frequencies of these peaks are equal to those of Fibonacci numbers. The appearance of such frequencies in the fluctuation spectrum indicates that the fluctuations studied bear a resemblance to processes occurring in open dissipative dynamic systems. The methods developed in the theory of these systems can, in principle, be used to study giant fluctuations. 相似文献
19.
The Hall coefficient has been measured for (a) liquid CuTe, AgTe and AuTe2 and (b) liquid Cu-Sn alloy. The results are discussed in terms of the possible semiconducting nature of liquids comprising group (a) and in terms of bound state formation around the Sn atoms for those in group (b). 相似文献
20.
Stacked two dimensional electron systems in transverse magnetic fields exhibit three dimensional fractional quantum Hall phases. We analyze the simplest such phases and find novel bulk properties, e.g. , irrational braiding. These phases host "one and a half" dimensional surface phases in which motion in one direction is chiral. We offer a general analysis of conduction in the latter by combining sum rule and renormalization group arguments, and find that when interlayer tunneling is marginal or irrelevant they are chiral semimetals that conduct only at T > 0 or with disorder. 相似文献