Antiferromagnetic ordering of organic Mott insulator λ\lambda-(BEDSe-TTF)2_2GaCl4_4

The band structure and magnetic properties of organic charge-transfer salt $\lambda$-(BEDSe-TTF)$_2$GaCl$_4$ (BEDSe-TTF: bis(ethylenediseleno)tetrathiafulvalene; abbreviated as $\lambda$-BEDSe) are investigated. The reported crystal structure is confirmed using X-ray diffraction measurements, and the transfer integrals are calculated. The degree of electron correlation $U/W$ ($U$: on-site Coulomb repulsion, $W$: bandwidth) of $\lambda$-BEDSe is larger than one and comparable to that of the isostructural Mott insulator $\lambda$-(ET)$_2$GaCl$_4$ (ET: bis(ethylenedithio)tetrathiafulvalene, abbreviated as $\lambda$-ET), whereas the $U/W$ of the superconducting salt $\lambda$-(BETS)$_2$GaCl$_4$ (BETS: bis(ethylenedithio)tetraselenafulvalene) is smaller than one. $^{13}$C-NMR and $\mu$SR measurements revealed that $\lambda$-BEDSe undergoes an antiferromagnetic (AF) ordering below $T_{\rm N} = 22$~K. In the AF state, discrete $^{13}$C-NMR spectra with a remaining central peak are observed, indicating the commensurate AF spin structure also observed in $\lambda$-ET. The similarity between the structural and magnetic properties of $\lambda$-BEDSe and $\lambda$-ET suggests that both salts are in the same electronic phase, i.e., the physical properties of $\lambda$-BEDSe can be understood by the universal phase diagram of bandwidth-controlled $\lambda$-type organic conductors obtained by donor molecule substitution.Comment: 12 pages, 9 figures, accepted for publication in Phys. Rev.

Antibiotic R2, a new angucyclinone compound from Streptosporangium sp. Sg3

Antibiotic R2, a new angucyclinone compound from Streptosporangium sp. Sg

The BepiColombo–Mio Magnetometer en Route to Mercury

The fluxgate magnetometer MGF on board the Mio spacecraft of the BepiColombo mission is introduced with its science targets, instrument design, calibration report, and scientific expectations. The MGF instrument consists of two tri-axial fluxgate magnetometers. Both sensors are mounted on a 4.8-m long mast to measure the magnetic field around Mercury at distances from near surface (initial peri-center altitude is 590 km) to 6 planetary radii (11640 km). The two sensors of MGF are operated in a fully redundant way, each with its own electronics, data processing and power supply units. The MGF instrument samples the magnetic field at a rate of up to 128 Hz to reveal rapidly-evolving magnetospheric dynamics, among them magnetic reconnection causing substorm-like disturbances, field-aligned currents, and ultra-low-frequency waves. The high time resolution of MGF is also helpful to study solar wind processes (through measurements of the interplanetary magnetic field) in the inner heliosphere. The MGF instrument firmly corroborates measurements of its companion, the MPO magnetometer, by performing multi-point observations to determine the planetary internal field at higher multi-pole orders and to separate temporal fluctuations from spatial variations