Magnetotail structures in a simulated Earth's magnetosphere

The structure of the magnetotail is investigated in a laboratory simulated magnetosphere. Particular emphasis is placed on the region of distant magnetotail where the closed field line region of the plasma sheet terminates and the process of reconnection takes place. Our study builds upon the previous investigation of the magnetotail where the main results were based on the magnetic field measurements in the tail region of the simulated magnetosphere. In this paper, more elaborate measurements of plasma flow and electric field are presented. Besides these measurements, this region of distant magnetotail is also explored by high resolution imaging with a gated optical imager (GOI) and by digital image analysis. These images clearly reveal a Y-type magnetic neutral line for the northward 'interplanetary' field (IMF) and a usual X-type for the southward IMF that confirms our previous results deduced from the magnetic field measurements. In the neighborhood of these neutral points a strong component of dawn to dusk electric field (E(sub y)) and a counterstreaming plasma flow is also observed. Plasma flow is measured by using a double sided Faraday cup which is also used to measure the y-component of tail current (J(sub y)) at different locations. These measurements reveal that the tail current is not carried by ions as previously thought, rather it is carried by electrons alone

Phase Separation in A-site Ordered Perovskite Manganite LaBaMn2_2O6_6 Probed by 139^{139}La and 55^{55}Mn NMR

$^{139}$La- and $^{55}$Mn-NMR spectra demonstrate that the ground state of the A-site ordered perovskite manganite LaBaMn$_2$O$_6$ is a spatial mixture of the ferromagnetic (FM) and antiferromagnetic (AFI(CE)) regions, which are assigned to the metallic and the insulating charge ordered state, respectively. This exotic coexisting state appears below 200 K via a first-order-like formation of the AFI(CE) state inside the FM one. Mn spin-spin relaxation rate indicates that the FM region coexisting with the AFI(CE) one in LaBaMn$_2$O$_6$ is identical to the bulk FM phase of the disordered form La$_{0.5}$Ba$_{0.5}$MnO$_3$ in spite of the absence of A-site disorder. This suggests mesoscopic rather than nanoscopic nature of FM region in LaBaMn$_2$O$_6$\@.Comment: 4 pages, 4 figures, to be published in Phys. Rev. Let

Statistical properties of spectral fluctuations for a quantum system with infinitely many components

Extending the idea formulated in Makino {\it{et al}}[Phys.Rev.E {\bf{67}},066205], that is based on the Berry--Robnik approach [M.V. Berry and M. Robnik, J. Phys. A {\bf{17}}, 2413], we investigate the statistical properties of a two-point spectral correlation for a classically integrable quantum system. The eigenenergy sequence of this system is regarded as a superposition of infinitely many independent components in the semiclassical limit. We derive the level number variance (LNV) in the limit of infinitely many components and discuss its deviations from Poisson statistics. The slope of the limiting LNV is found to be larger than that of Poisson statistics when the individual components have a certain accumulation. This property agrees with the result from the semiclassical periodic-orbit theory that is applied to a system with degenerate torus actions[D. Biswas, M.Azam,and S.V.Lawande, Phys. Rev. A {\bf 43}, 5694].Comment: 6 figures, 10 page

Simplicity of eigenvalues in the Anderson model

We give a simple, transparent, and intuitive proof that all eigenvalues of the Anderson model in the region of localization are simple