Raman scattering in LiNiPO₄ single crystal

The complete Raman spectra of a single crystal of LiNiPO₄ for a wide temperature range are reported. Among the 36 Raman-active modes predicted by group theory, 33 have been detected. The analysis of the spectra in terms of internal modes of the (PO₄)³⁻ group and of external modes is done with success. Besides, the multiphonon Raman scattering is discussed. Low-frequency lines, observed in the antiferromagnetic phase, are assigned to magnon scattering and are discussed briefly

Phonons and magnons in stripe-ordered nickelates. A Raman scattering study

Electronic correlation effects in La₂-xSrxNiO₄ (x = 1/3 and 0.225) lead to spontaneous phase separation into microscopic spin/charge stripes with commensurate and incommensurate order, respectively. Raman scattering experiments on such single crystalline materials show a rich phenomenology of phonon and magnon anomalies due to the new, self-organized periodicities. These effects are observable as function of temperature but can also be induced by cooling in a seemingly small magnetic field leading to a reorganization of stripe structure

Gene Expression Atlas update—a value-added database of microarray and sequencing-based functional genomics experiments

Gene Expression Atlas (http://www.ebi.ac.uk/gxa) is an added-value database providing information about gene expression in different cell types, organism parts, developmental stages, disease states, sample treatments and other biological/experimental conditions. The content of this database derives from curation, re-annotation and statistical analysis of selected data from the ArrayExpress Archive and the European Nucleotide Archive. A simple interface allows the user to query for differential gene expression either by gene names or attributes or by biological conditions, e.g. diseases, organism parts or cell types. Since our previous report we made 20 monthly releases and, as of Release 11.08 (August 2011), the database supports 19 species, which contains expression data measured for 19 014 biological conditions in 136 551 assays from 5598 independent studies

Analysis of the low-frequency spectrum of the cubic noncentrosymmetric ferrimagnet Cu2OSeO3

The IR reflectance spectra of the cubic noncentrosymmetric ferrimagnet Cu2OSeO3 (T-C approximate to 60 K) were investigated in the temperature range 10-80 K. Detailed analysis of the symmetry and composition of vibrational modes was conducted on the basis of Raman scattering data and data obtained in this investigation. 68 out of 69 modes consistent with the crystal lattice symmetry were revealed. Some spectral features found in the magnetically ordered phase were studied. The bands at 280 and 421 cm(-1) related to the spectrum of two-magnon light scattering were observed. Dynamic magnetoelectric coupling was found to be responsible for the intensity redistribution in the Raman and IR spectra for the threefold degenerate modes of F-symmetry (modes at 84, 205, and 269 cm(-1)). No change associated with magnetic ordering was observed in the symmetry of the crystal structure. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4723668