This paper shows that matter-wave interferometers employing low-velocity neutral atoms can be used as inertial sensors with sensitivities that exceed those of conventional mechanical sensors and multiple circuit optical interferometers by many powers of ten. The energy and mass dependence of the phase shifts that are due to rotation and acceleration are different. Thus a pair of interferometers with different energies and/or masses can perform simultaneous independent measurements of rotation and acceleration. A proposed configuration is one formed by a sequence of planar diffraction gratings operating in high order. Gratings consist of near-resonant standing-wave laser beams. Laser decelerated and cooled atomic beams provide a suitable source. Path curvature due to acceleration and rotation is canceled by magnetic field gradients that produce an effective magnetic levitation of the atoms in a feedback arrangement that maintains null phase shift.
The local densities of states for d-bands of Fe clusters composed of one to four Fe atoms in Zr(Fe1−xCox)2 are calculated by the recursion method. The magnetic properties of the clusters are examined by the band model. The calculated local magnetic moments on the Fe atoms in the clusters are nearly saturated in the paramagnetic virtual crystal of Zr(Fe1−xCox)2. The calculated magnetic moments, magnetic energies and the local density of states are affected only a little by the size of the cluster or the spin configurations of the local magnetic moments on the Fe atoms in the cluster.
The magnetism of Laves phase compounds RMn2 is reviewed. The conditions for the onset of Mn moments and the type of spin fluctuations of the Mn sublattice are discussed. It is shown that the Mn moments, if they exist, are unstable and easily collapse on raising the temperature or on substituting R or Mn by a third element with a smaller atomic volume. By analyzing the thermal expansion curves, the amplitudes of spin fluctuations in YMn2 and related compounds are estimated.
We describe a new method for calculating the orbital contribution to the susceptibility and neutron magnetic form factor of paramagnetic transition metals. The method has been developed by us over the past four years, and the computational details and results will be published elsewhere. In this paper we discuss the theoretical issues, which include a justification of the basic approximation and the estimate of errors. It is shown that it gives reliable results for the size of the susceptibility and the overall shape of the form factor, but is probably not sufficiently accurate to account for the anisotropy in the orbital moment distribution.
The effect of collective electron oscillations at the surface of the metal compounds has been discussed in the X-ray absorption spectra of several metal compounds. The effect of double plasmon oscillations has also been discussed on the X-ray K or L-absorption edges. As a result of our work, various unexplained chemical shifts have been explained.
Using Monte Carlo simulation the domain growth in the two-dimensional Ising system in the presence of a small amount of impurities or antiferromagnetic bonds is studied. The domain size R grows following the power law R(t)∝tn, and the exponent n decreases with the concentration of impurities or antiferromagnetic bonds. It is found that the effect of antiferromagnetic bonds on the reduction of n is more remarkable than that of impurities.
Critical point exponents for the paramagnetic susceptibility in Co and Fe have been derived from the measurements published by Develey. The exponent, γ, for the linear reduced temperature (1 - T/Tc) is the same as that for the non-linear reduced temperature (1 − Tc/T). The extension to measurements made on Fe-Si alloys broke down for Si concentrations of more than c = 0.07. In that case, γ was very different from the value for Fe; it was not possible to judge whether this difference was real or was due to uncertainty in the value of Tc which, for c > 0.07, has three different published values at least.
The 3E2g(e32ga11g) ground state of chromocene is treated as a system consisting of two holes, one in the e2g and the other in the a1g orbital. By a suitable choice of the basis vectors the vibronic eigenvalue equations of this case are transformed into isomorphic forms to the corresponding equation for the one electron case. The method of canonical transformation and variational approach developed in part I therefore is applied to chromocene also. The variational wavefunctions and energies are used to explain the EPR and Raman spectroscopy results on the complex.
A new interpretation of the formula for transition probabilities in quantum theory is proposed, based on the relativistic version of the Feynman path integral. According to this interpretation both the transition amplitude and its complex conjugate are treated on equal footing. They differ only in having opposite directions of the intrinsic time. It is conjectured that both processes, the one that corresponds to the amplitude and the one that corresponds to the complex conjugate amplitude, are equally real and that they both take place in space-time. Every time a measurement occurs, the direction of the intrinsic time is reversed. In this formulation the dilemma faced by Schrödinger in 1926, which sign of i to choose in the wave equation, does not arise.
The liquidus curves of twenty five simple-eutectic binary alloys are constructed using the semi-empirical theory of heats of formation developed by Miedema and coworkers. Overall the predictions of this theory are quite correct. In cases where discrepancies exist, it is possible to improve the results by retaining the formal expression of the heat of formation proposed by Miedema, but modifying the prescribed values of the heats of solution.
We incorporate the particle-hole atraction into the periodic Anderson model (PAM) to describe the mixed valence systems. We have reduced the model with excitonic correlations into an effective PAM using a full mean-field decoupling for the particle-hole attraction as suggested by Khomskii and Kocharyan. The self-consistency equations for the spin dependent average f-, d-level occupations nfσ and ndσ respectively and the excitonic correlations, γσ have been derived. The influence of various model parameters, namely, the 4f-level position Ef, the hybridization strenght V and the particle-hole attraction strength Ufd has been studied on the temperature dependence of the static magnetic susceptibility. We conclude that the excitonic correlations help in destabilizing the magnetic order and also in broadening of the susceptibility peak in the low temperature region. Results are in good agreement with the general features experimentally observed in several mixed valence compounds. From the susceptibility curves obtained here and those already existing in literature a remarkable feature comes out. Whatever be the approximation used, even for two mutually exclusive approximation schemes like small and infinite Coulomb repulsion, the qualitative behaviour of the susceptibility remains the same.
Already in 1935, Schrödinger assembled all prerequisites for a proof of Bell-type inequalities, namely: (i) a suitable two-particle state; (ii) a sufficient number of observables which are correlated in that state; and (iii) a tentative interpretation of these correlations in the spirit of local hidden-variables theories. The inequalities derived here from these assumptions are violated in quantum mechanics, which shows once more that quantum correlations cannot be understood in terms of local hidden-variables theories. This was realized before Bell (1964), since all previous authors — including Schrödinger — focused their attention to perfect correlations and underestimated the importance of the imperfect ones.
Gignoux et al. found that Y2Ni7, which is paramagnetic at T = 0 K, becomes ferromagnetic when the temperature is raised to Ts ⋍ 7 K and then it again becomes paramagnetic at Tc ⋍ 60 K. Recently we pointed out how the consideration of the electron-phonon interaction facilitates our understanding of such an observation. In this paper we further extend our analysis by using the more detailed results of the electronic structure calculation recently published by Shimizu and Inoue and again confirm the importance of the role of phonons.
We have investigated the drain current-drain voltage characteristics and the spectral noise intensity of the drain current of (111) n-channel MOSFET's at T = 4.2 K. At T = 4.2 K the drain current-drain voltage characteristics showed a hysteresis which was not observed at T =77 K and at room temperature. A qualitative explanation of this hysteresis is given in terms of electron transfer from high mobility valleys to low mobility valleys due to hot electrons. In the spectra of the current noise three contributions could be distinguished: 1/ƒ-noise, white noise and generation-recombination noise. The 1/ƒ-noise is interpreted as number fluctuations noise. The effective trap density was found to be 2.3 × 1022 m-3. At low drain voltages the white noise can be interpreted as diffusion noise. At higher drain voltages extra noise is observed over and above diffusion noise. This extra noise may be inter-valley noise. The generation-recombination noise was very sensitive to the gate voltage. A tentative explanation can be given if it is assumed that the traps which cause this noise have a non-uniform energy distribution.
A mathematical description of axi-symmetrical bubbles as well as experimental results related to their behaviour at low pressures is presented. It is suggested that in vacuum the film forming the bubble changes into a quasi-membrane.
Finite-temperature magnetic properties of Co-Cr superlattices have been studied for the first time within the framework of itinerant-electron theory using the tight-binding model and single-site spin fluctuation theory. The distributions of local magnetic moments on Co and Cr layers are calculated as a function of the temperature in four-layer (1 Co + 3 Cr) bcc superlattices. The interfaces have the [001] orientation. We find that Co magnetic moments couple ferromagnetically across the Co/Cr interface while Cr magnetic moments are stabilized in the commensurate antiferromagnetic state. The temperature dependence of the Co moment (and total magnetization) deviates significantly from the Brillouin function. We suggest that this arises from a weak magnetic interaction across the Co/Cr interface. The theoretical implications for other ferromagnetic/antiferromagnetic interfaces are also discussed.
Because quantum mechanics has severe interpretational problems which have not been resolved within the theory of quantum mechanics, a new approach to basic physics is proposed. Elementary particles are hypothesized to be the constructive interference peaks of a wave system extending throughout the universe. It is then shown that the wave system is in the lowest energy state when the wave modes constructively interfere. Consequently, the interference peaks are stable entities since any reduction in the constructive interference would raise the energy of the system. The Schrödinger equation is derived from the wave system based on the Lorentz invariance of the classical wave equation subject to the condition that the constructive interference peaks remain in-phase with the wave modes. In addition, the results of the two-slit interference experiment are logically explained.
We investigate the ferromagnetism of Ni in the spin fluctuation theory developed by us based on the work of Hertz and Klenin. Quantum effects are taken into consideration in calculating the amplitudes of the fluctuation. A good agreement with experiment is obtained for the temperature dependence of the spontaneous magnetization. The paramagnetic susceptibility is also calculated. Further we clarifu the details of the contribution of the fluctuation to the magnetism.
The contribution of the Pr3+ ions to the magnetocrystalline anisotropy constants K1 and K2 in Pr2Fe14B as well as its temperature dependence have been calculated within a single-ion theory. The calculated results agree with experiment. The anisotropy constants due to the Pr3+ ions in PrCo5 were also calculated. By considering all terms of the crystal field (CF), including the Co contribution, we obtained results which were again in good agreement with experiment.
Amorphous and partially crystalline ferromagnetic Fe80B20 alloys have been prepared by varying the quench rate during the melt spinning process. Using Mössbauer spectroscopy we traced the occurence of the crystalline FeB phases and their parameters. We found that the sequence of encounter of the phases is reversed when compared with annealing experiments.
