Time Dependent Effects and Transport Evidence for Phase Separation in La_{0.5}Ca_{0.5}MnO_{3}

The ground state of La_{1-x}Ca_{x}MnO_{3} changes from a ferromagnetic metallic to an antiferromagnetic charge-ordered state as a function of Ca concentration at x ~ 0.50. We present evidence from transport measurements on a sample with x = 0.50 that the two phases can coexist, in agreement with other observations of phase separation in these materials. We also observe that, by applying and then removing a magnetic field to the mainly charge-ordered state at some temperatures, we can "magnetically anneal" the charge order, resulting in a higher zero-field resistivity. We also observe logarithmic time dependence in both resistivity and magnetization after a field sweep at low temperatures.Comment: 9 pages, LATEX, 3 postscript figure

Anomalous Microfluidic Phonons Induced by the Interplay of Hydrodynamic Screening and Incompressibility

We investigate the acoustic normal modes ("phonons") of a 1D microfluidic droplet crystal at the crossover between 2D flow and confined 1D plug flow. The unusual phonon spectra of the crystal, which arise from long-range hydrodynamic interactions, change anomalously under confinement. The boundaries induce weakening and screening of the interactions, but when approaching the 1D limit we measure a marked increase in the crystal sound velocity, a sign of interaction strengthening. This non-monotonous behavior of the phonon spectra is explained theoretically by the interplay of screening and plug flow.Comment: http://link.aps.org/doi/10.1103/PhysRevLett.99.124502 http://www.weizmann.ac.il/complex/tlusty/papers/PhysRevLett2007.pd

Calculation of minor hysteresis loops under metastable to stable transformations in vortex matter

We present a model in which metastable supercooled phase and stable equilibrium phase of vortex matter coexist in different regions of a sample. Minor hysteresis loops are calculated with the simple assumption of the two phases of vortex matter having field-independent critical current densities. We use our earlier published ideas that the free energy barrier separating the metastable and stable phases reduces as the magnetic induction moves farther from the first order phase transition line, and that metastable to stable transformations occur in local regions of the sample when the local energy dissipation exceeds a critical value. Previously reported anomalous features in minor hysteresis loops are reproduced, and calculated field profiles are presented.Comment: 9pages, 7 figure

Self-adjoint extensions and SUSY breaking in Supersymmetric Quantum Mechanics

We consider the self-adjoint extensions (SAE) of the symmetric supercharges and Hamiltonian for a model of SUSY Quantum Mechanics in $\mathbb{R}^+$ with a singular superpotential. We show that only for two particular SAE, whose domains are scale invariant, the algebra of N=2 SUSY is realized, one with manifest SUSY and the other with spontaneously broken SUSY. Otherwise, only the N=1 SUSY algebra is obtained, with spontaneously broken SUSY and non degenerate energy spectrum.Comment: LaTeX. 23 pages and 1 figure (minor changes). Version to appear in the Journal of Physics A: Mat. and Ge

A non-destructive analytic tool for nanostructured materials : Raman and photoluminescence spectroscopy

Modern materials science requires efficient processing and characterization techniques for low dimensional systems. Raman spectroscopy is an important non-destructive tool, which provides enormous information on these materials. This understanding is not only interesting in its own right from a physicist's point of view, but can also be of considerable importance in optoelectronics and device applications of these materials in nanotechnology. The commercial Raman spectrometers are quite expensive. In this article, we have presented a relatively less expensive set-up with home-built collection optics attachment. The details of the instrumentation have been described. Studies on four classes of nanostructures - Ge nanoparticles, porous silicon (nanowire), carbon nanotubes and 2D InGaAs quantum layers, demonstrate that this unit can be of use in teaching and research on nanomaterials.Comment: 32 pages, 13 figure

Like Sign Dilepton Signature for Gluino Production at LHC with or without R Conservation

The isolated like sign dilepton signature for gluino production is investigated at the LHC energy for the $R$ conserving as well as the $L$ and $B$ violating SUSY models over a wide range of the parameter space. One gets viable signals for gluino masses of 300 and 600 GeV for both $R$ conserving and $L$ violating models, while it is less promising for the $B$ violating case. For a 1000 GeV gluino, the $L$ violating signal should still be viable; but the $R$ conserving signal becomes too small at least for the low luminosity option of LHC.Comment: (e-mail: [email protected]) Latex: No. of pages 21, no. of figures 6 - available on reques

Ibadah dan keadilan sosial: Interpretasi sosio-historis Amos 8:4-8 bagi hidup bergereja

This paper is an attempt to explore the deepest message of Amos 8:4-8 with the socio-historical interpretation approach. Progress and prosperity that occurred in northern Israel in the 8th century BC gave birth to religious euphoria. The euphoria can be seen from the crowded places of worship visited by people to offer praise and sacrifice. But unfortunately, religious life has no impact at all on their social life, greed and oppression occur here and there. This is the background to the criticism of the prophet found in Amos 8: 4-8. The socio-historical interpretation approach used in this study is a tool to explore the meaning of the text by investigating the social context of the community when the text was written. The results of the interpretation explain that the middle and upper classes form an economic system that harms the lower classes, namely small farmers and urbanites. Worship is useless if it does not give rise to social care for others. Abstrak Tulisan ini adalah suatu upaya menggali pesan terdalam teks Amos 8:4-8. Kemajuan dan kemakmuran yang terjadi di Israel Utara pada abad 8 sM melahirkan euforia keagamaan. Euforia itu tampak dengan ramainya tempat-tempat peribadatan yang dikunjungi umat untuk menyampaikan pujian dan korban. Tetapi sayangnya kehidupan beragama tersebut tidak berdampak sama sekali bagi kehidupan sosial mereka, ketamakan serta penindasan terjadi di sana-sini. Hal inilah yang menjadi latar belakang kecaman nabi yang terdapat pada Amos 8:4-8. Interpretasi sosio-historis yang digunakan dalam penelitian ini adalah alat untuk menggali makna teks dengan menyelidiki konteks sosial masyarakat saat teks dituliskan. Hasil penafsiran menjelaskan bahwa kalangan menengah dan atas membentuk sistem perekonomian yang merugikan kalangan bawah yaitu petani kecil dan kaum urban. Ibadah menjadi sia-sia belaka bila tidak melahirkan sikap kepedulian sosial terhadap sesamanya