Nanoscale Suppression of Magnetization at Atomically Assembled Manganite Interfaces

Using polarized X-rays, we compare the electronic and magnetic properties of a La(2/3)Sr(1/3)MnO(3)(LSMO)/SrTiO(3)(STO) and a modified LSMO/LaMnO(3)(LMO)/STO interface. Using the technique of X-ray resonant magnetic scattering (XRMS), we can probe the interfaces of complicated layered structures and quantitatively model depth-dependent magnetic profiles as a function of distance from the interface. Comparisons of the average electronic and magnetic properties at the interface are made independently using X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD). The XAS and the XMCD demonstrate that the electronic and magnetic structure of the LMO layer at the modified interface is qualitatively equivalent to the underlying LSMO film. From the temperature dependence of the XMCD, it is found that the near surface magnetization for both interfaces falls off faster than the bulk. For all temperatures in the range of 50K - 300K, the magnetic profiles for both systems always show a ferromagnetic component at the interface with a significantly suppressed magnetization that evolves to the bulk value over a length scale of ~1.6 - 2.4 nm. The LSMO/LMO/STO interface shows a larger ferromagnetic (FM) moment than the LSMO/STO interface, however the difference is only substantial at low temperature.Comment: 4 pages, 4 figure

On the error term in Weyl's law for the Heisenberg manifolds (II)

In this paper we study the mean square of the error term in the Weyl's law of an irrational $(2l+1)$-dimensional Heisenberg manifold . An asymptotic formula is established

Granular Media under Vibration in Zero Gravity: Transition from Rattling to Granular Gas

We report on different experimental behaviours of granular dissipative matter excited by vibration as studied during the 43rd ESA campaign of Airbus A300-0g from CNES. The effect of g-jitter is quantified through the generation of a rattle effect. The French-European team's electromagnetic set-up is used, with 20Hz cam recording and high speed camera for a short duration (1s) during each parabola.Comment: Poudres et Grains 201

Two-photon interference with two independent pseudo-thermal sources

The nature of two-photon interference is a subject that has aroused renewed interest in recent years and is still under debate. In this paper we report the first observation of two-photon interference with independent pseudo-thermal sources in which sub-wavelength interference is observed. The phenomenon may be described in terms of the classical statistical distribution of the two sources and their optical transfer functions.Comment: Phys. Rev. A 74, 053807 (2006

The Revival of Galactic Cosmic Ray Nucleosynthesis?

Because of the roughly linear correlation between Be/H and Fe/H in low metallicity halo stars, it has been argued that a ``primary'' component in the nucleosynthesis of Be must be present in addition to the ``secondary'' component from standard Galactic cosmic ray nucleosynthesis. In this paper we critically re-evaluate the evidence for the primary versus secondary character of Li, Be, and B evolution, analyzing both in the observations and in Galactic chemical evolution models. While it appears that [Be/H] versus [Fe/H] has a logarithmic slope near 1, it is rather the Be-O trend that directly arises from the physics of spallation production. Using new abundances for oxygen in halo stars based on UV OH lines, we find that the Be-O slope has a large uncertainty due to systematic effects, rendering it difficult to distinguish from the data between the secondary slope of 2 and the primary slope of 1. The possible difference between the Be-Fe and Be-O slopes is a consequence of the variation in O/Fe versus Fe: recent data suggests a negative slope rather than zero (i.e., Fe $\propto$ O) as is often assumed. In addition to a phenomenological analysis of Be and B evolution, we have also examined the predicted LiBeB, O, and Fe trends in Galactic chemical evolution models which include outflow. Based on our results, it is possible that a good fit to the LiBeB evolution requires only traditional the Galactic cosmic ray spallation, and the (primary) neutrino-process contribution to B11. We thus suggest that these two processes might be sufficient to explain Li6, Be, and B evolution in the Galaxy, without the need for an additional primary source of Be and B.Comment: 25 pages, latex, 8 ps figures, figure 1 correcte

Non-linear microwave impedance of short and long Josephson Junctions

The non-linear dependence on applied $ac$ field ($b_{\omega}$) or current ($i_{\omega}$) of the microwave (ac) impedance $R_{\omega}+iX_{\omega}$ of both short and long Josephson junctions is calculated under a variety of excitation conditions. The dependence on the junction width is studied, for both field symmetric (current anti-symmetric) and field anti-symmetric (current symmetric) excitation configurations.The resistance shows step-like features every time a fluxon (soliton) enters the junction, with a corresponding phase slip seen in the reactance. For finite widths the interference of fluxons leads to some interesting effects which are described. Many of these calculated results are observed in microwave impedance measurements on intrinsic and fabricated Josephson junctions in the high temperature superconductors, and new effects are suggested. When a $$ field ($b_{dc}$) or current ($i_{dc}$) is applied, interesting phase locking effects are observed in the ac impedance $Z_{\omega}$. In particular an almost periodic dependence on the dc bias is seen similar to that observed in microwave experiments at very low dc field bias. These results are generic to all systems with a $\cos (\phi)$ potential in the overdamped limit and subjected to an ac drive.Comment: 7 pages, 11 figure