Hall Systems Research Articles

Effects of post-heat treatment on the characteristics of chalcopyrite CuInSe 2 film deposited by successive ionic layer absorption and reaction method

The influence of annealing effects in CuInSe 2 ternary films prepared by successive ionic layer absorption and reaction method has been investigated. The films have firstly been deposited on glass substrates at room temperature and then heat-treated under Ar atmosphere at various annealing temperatures. CuInSe 2 films were characterized using X-ray diffraction (XRD), scanning electron microscopy, X-ray photoelectron spectra, optical absorption spectrum and Hall system. XRD results showed that the proper post-annealing process can lead to a complete formation of chalcopyrite structure CuInSe 2 with high degree of preferred orientation towards (112) reflection. After annealing process, the composition of annealed films was close to the standard stoichiometry and O, Cl impurities decreased. The direct band gap increased from 0.94 to 0.98 eV and resistivity showed a big decrease with the increase of annealing temperature.

Metal-Insulator Transition Tuned by External Gates in Hall Systems with Constrictions

The nature of a metal-insulator transition tuned by external gates in quantum Hall systems with point constrictions, as reported in recent experiments [S. Roddaro, Phys. Rev. Lett. 95, 156804 (2005)10.1103/PhysRevLett.95.156804], is examined. We attribute this phenomenon to a splitting of the integer edge into conducting and insulating stripes, the latter wide enough to allow for the stability of the edge structure. Interchannel impurity scattering and interchannel Coulomb interactions do not destabilize this picture.

High-pressure oxygen treatment of ZnO thin films

ZnO thin films have been deposited on Sapphire (0 0 0 1) substrate at 500 °C by the pulsed laser deposition (PLD). The grown samples have been treated under the high pressure oxygen (5 atm) for 24, 72, 240 and 480 h, respectively. The prepared thin films have been characterized by X-ray diffractometer (XRD), photoluminescence (PL) and Hall systems. From PL studies, it is observed that the intensities of defect peaks at 2.1 and 2.5 eV have increased slightly, while the near band edge (NBE) emission has no change in its intensity. From XRD, the FWHM has rapidly decreased until 24 h and after that it has been stabilized. From the Hall measurement, we have found that the carrier concentration has decreased, while the mobility has increased by the oxygen treatment.

MeV Ion Beam Bombardments Effects on the Thermoelectric Properties of Zn4Sb3 / CeFe(4-x)CoxSb12 Nano-Layered Superlattices

ABSTRACTWe prepared multilayers of semiconducting half-heusler β-Zn4Sb3 and skutterudites CeFe(4-x)CoxSb12 compound thin films by ion beam assisted deposition (IBAD) system for the application of thermoelectric (TE) materials. Rutherford backscattering spectrometry (RBS) was used to analyze the composition of thin films. The thin films were then bombarded by 5 MeV Si ions for generation of nanodots in the films. We measured the cross-plane thermal conductivity by a house developed 3ω-method system, cross-plane Seebeck coefficient by a (MMR) Seebeck system, and cross plane electrical conductivity of these nanolayered systems by a (MMR) Hall system before and after bombardment. Both β-Zn4Sb3 and CeFe(4-x)CoxSb12 systems have been identified as promising thermoelectric materials for the application of thermal-to-electrical energy conversion. The nanodots produced by MeV ion beam can cause significant change in both electrical and thermal conductivity of thin films, thus improving the efficiency. The MeV ion-beam bombardment resulted in decrease in the thermal conductivity of thin films and increase in the efficiency of thermal-to-electrical energy conversion.

Quantum Oscillation of Hall Resistance in the Extreme Quantum Limit of an Organic Conductor(TMTSF)2ClO4

We report resistance and magnetic torque experiments under a high magnetic field up to 45 T in a three dimensional quantum Hall (QH) system (TMTSF)(2)ClO(4), where TMTSF = tetramethyltetraselenafulvalene. The Hall resistance shows huge oscillations accompanied with sign reversal after the final QH state, where the Landau level filling factor is unity, is removed above 26 T. The magnetic torque also oscillates with the field. The results suggest that a novel quantum state, where the character of the carriers periodically changes with the field, is stabilized in the extreme quantum limit.

Spectral and Temporal Resolution of THz Detectors based on Quantum Hall Devices with various Geometries

ABSTRACTQuantum Hall (QH) systems can work as very sensitive THz detectors. In this work we report on the spectral and temporal resolution of the QH THz photodetectors with different geometries. The spectral resolution of THz QH detectors is of the order of 1-3 meV depending on bias conditions. The temporal resolution of QH detectors depends on the device geometry. For Corbino-shaped detectors we have demonstrated the devices with response times from 10 ns to over 200 ns.

Modularity in the lattice of ?-permutable subgroups

For a Hall system Σ of a finite solvable group G, it is known that the set % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaafiart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWefv3ySLgznf % gDOfdaryqr1ngBPrginfgDObYtUvgaiuaacqWFpepucaGGOaGaeu4O % dmLaaiykaaaa!442A! $$\mathcal{P}(\Sigma )$$ of Σ-permutable subgroups is a sublattice of the subgroup lattice of G. We investigate the class SPM of groups in which the lattice % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaafiart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWefv3ySLgznf % gDOfdaryqr1ngBPrginfgDObYtUvgaiuaacqWFpepucaGGOaGaeu4O % dmLaaiykaaaa!442A! $$\mathcal{P}(\Sigma )$$ is modular. We prove that if % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaafiart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWefv3ySLgznf % gDOfdaryqr1ngBPrginfgDObYtUvgaiuaacqWFpepucaGGOaGaeu4O % dmLaaiykaaaa!442A! $$\mathcal{P}(\Sigma )$$ is modular, then U⊥ V for all % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaafiart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaamyvaiaacY % cacaWGwbGaeyicI48efv3ySLgznfgDOfdaryqr1ngBPrginfgDObYt % UvgaiuaacqWFpepucaGGOaGaeu4OdmLaaiykaaaa!4813! $$U,V \in \mathcal{P}(\Sigma )$$ (an evidently stronger condition). Both of these phenomena—the modularity of % MathType!Translator!2!1!AMS LaTeX.tdl!TeX -- AMS-LaTeX! % MathType!MTEF!2!1!+- % feaafiart1ev1aqatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaWefv3ySLgznf % gDOfdaryqr1ngBPrginfgDObYtUvgaiuaacqWFpepucaGGOaGaeu4O % dmLaaiykaaaa!442A! $$\mathcal{P}(\Sigma )$$ and whether two Σ-permutable subgroups U and V permute with each other—are shown to be determined “locally,” by what happens at each prime. The class SPM is shown to be quotient closed, but not direct product or subgroup closed.

Computing Subgroups by Exhibition in Finite Solvable Groups

We present practical algorithms to compute subgroups such as Hall systems, system normalizers,F -normalizers and F -covering subgroups in finite solvable groups. An application is an algorithm to calculate head complements in finite solvable groups; that is, complements which are closely related to maximal subgroups. Our algorithms use the technique of exhibiting subgroups.

Hamiltonian theory of gaps, masses, and polarization in quantum Hall states

I furnish details of the hamiltonian theory of the FQHE developed with Murthy for the infrared, which I subsequently extended to all distances and apply it to Jain fractions \nu = p/(2ps + 1). The explicit operator description in terms of the CF allows one to answer quantitative and qualitative issues, some of which cannot even be posed otherwise. I compute activation gaps for several potentials, exhibit their particle hole symmetry, the profiles of charge density in states with a quasiparticles or hole, (all in closed form) and compare to results from trial wavefunctions and exact diagonalization. The Hartree-Fock approximation is used since much of the nonperturbative physics is built in at tree level. I compare the gaps to experiment and comment on the rough equality of normalized masses near half and quarter filling. I compute the critical fields at which the Hall system will jump from one quantized value of polarization to another, and the polarization and relaxation rates for half filling as a function of temperature and propose a Korringa like law. After providing some plausibility arguments, I explore the possibility of describing several magnetic phenomena in dirty systems with an effective potential, by extracting a free parameter describing the potential from one data point and then using it to predict all the others from that sample. This works to the accuracy typical of this theory (10 -20 percent). I explain why the CF behaves like free particle in some magnetic experiments when it is not, what exactly the CF is made of, what one means by its dipole moment, and how the comparison of theory to experiment must be modified to fit the peculiarities of the quantized Hall problem.

Photoeffects in cobalt doped pyrite (FeS2) films

By indiffusion of a thin metallic cobalt layer into a pyrite film deposited by metal organic chemical vapour deposition (MOCVD), cobalt doped pyrite (FeS2) films have been prepared. The cobalt in these films acts as a donor and transforms the originally p-type into n-type conductivity. To our knowledge this is the first time that n-type pyrite films have been prepared. Compared to the undoped p-type pyrite films, the cobalt-diffused films exhibit a much higher photoconductivity, as revealed by time resolved microwave conductivity analysis.From Hall and conductivity measurements a charge carrier concentration of about 1020cm−3 and a Hall mobility of about 1.5cm2/(Vs) was calculated. This has to be compared with p-type pyrite films which do not show a Hall mobility above 0.1cm2/(Vs), the detection limit of our Hall system. By analytical techniques (Rutherford backscattering and photoelectron spectroscopy) it was confirmed that the increase of the photoactivity is a bulk property of the pyrite films and not merely due to a surface passivation (for instance, due to metallic CoS2). The presented results stimulate further experiments on in-situ-doping of pyrite by MOCVD and open the opportunity for the preparation of pn-junctions and pn-solar cells with pyrite.

Conductance of polypyrole irradiated with gamma rays to low doses

In order to investigate the effect of gamma irradiation on the conductivity of polypyrrole, dc and ac conductivity measurements were carried out by four-probe technique as a function of temperature and by using Hall system at room temperature, respectively. Both ac and dc conductivities were found to exhibit a maximum at 1.80 kGy dose value. The dc conductivity of irradiated polypyrrole films was found to vary exponentially with (T) −1 at high temperature, while (T) −1/4 dependence was observed at low temperature range.

Magneto-charge-transport from twisting arguments

We use a model of constant negative curvature Riemann surfaces to study the effect of coupling together several Hall systems on the Hall conductances of the individual systems. We find that on average, the coupling does not effect the conductances. The method we use is based on the fact that the average conductances are given by Chern numbers, and hence are stable when one varies parameters of the Hamiltonian, as long as eigenvalues do not cross. The parameters we change are the surface parameters, and we find the averaged conductances of the surface by 'twisting' and 'pinching' it. This method is applicable to other systems as well.

Criminal Law Systematized

The author is Professor Emeritus in Goettingen University. He has recently served as Guest Professor in the Seminar for Comparative Criminal Law of the New York University Law School. Dr. Honig has also recently served as Guest Professor in the Institute of Foreign Criminal Law of Freiburg University. In this article, the author reviews the second edition of Professor Jerome Hall's book entitled General Principles of Criminal Law. Dr. Honig observes that the attempt made by Hall in this work to systematize criminal law represents a trend new to the United States but of long standing in European countries. He further observes that Hall endeavors to base his principles upon many of the ultimate ideas of Western civilization, thereby inviting comparisons between the basic ideas of his system and those of the German theory of criminal law. Accordingly, Dr. Honig analyzes and appraises the principal elements of Hall's system, weighing them critically with the corresponding German theories.-EDITOR.

The electrical and illuminating equipment of the Eastman Theatre and School of Music

The Eastman Theatre and School of Music was designed and given to the people of Rochester by Mr. George Eastman for the purpose of teaching and presenting music in its best form and under ideal conditions, using motion pictures as a part of the educational scheme. A great deal of preliminary work was done in planning the auditorium and the lighting to be used during the exhibition of motion pictures so as to eliminate all possibility of visual fatigue. Illumination and Brightness Measurements. From preliminary investigations on a small scale, it was found that fairly high illumination levels can be obtained in the motion picture theatre without any detrimental effect upon the quality of the projected picture. In planning the lighting system of this theatre, an attempt was made to obtain illuminations of fairly high values distributed so as not to cause loss of quality in the picture. Equipment. The electrical installation of a modern theatre, of the size and scope of the Eastman, together with a School of Music embraces a variety of equipment and apparatus. Alternating current is used for the lights and constant speed motors, and direct current for the variable speed motors. The chandelier is equipped with a system of indirect lights, decorative candles, direct lights, and lights for scintillating the crystals. The picture booth is equipped with two sources of direct current one source from the street main, and another from a motor generator set driven by alternating current. The outside illumination consists of a flood lighting system for the entire facade of the building, marquise lights and display and attraction signs. There are six separate telephone systems in this installation — the outside bell system, automatic inside system, a production phone system in the Theatre and another in Kilbourn Hall, the ushers and ticket office system and the dressing room system. Time clocks are installed throughout the institution and a program clock operates buzzers in all studios. There is an employees' and a watchman's time recorder and time stamp system for keeping account of the time spent in the piano and organ practice rooms. A set of chimes in the corridors notify the audience when the intermissions are over. A complete local fire alarm system is installed and also boxes on the Theatre and Kilbourn Hall stages in connection with the city system. Speed indicators at the stage directors stand, music directors stand and organ console indicate the speed of the film and telegraph indicators similar to a marine engine room telegraph provide means for signalling the projectionist. A magnetic douser or system of magnetically controlled shutters provides means of instantaneously changing from one picture machine to another as the end of the reel is reached. Finally, a radio broadcasting station is installed for distributing the musical productions throughout the country and thus fulfilling the aim of this institution which is to promote the education in and appreciation of good music.