Schematic representation of unit cell structure of the phases: (a) tetragonal SnO₂; (b) orthorhombic SnO₂. Tin atoms (Sn) are represented in gray and oxygen atoms (O) in red. K. Momma and F. Izumi, J. Appl. Crystallogr., 2011, 44, 1272–1276.

Synchrotron radiation topography on modern sources, coupled with adequate CCD detectors, is producing (in a shorter time and with better resolution) results which could only be obtained, up to now, by using neutron topography. This is shown by two examples, carried out at the ESRF, on `exotic' antiferromagnetic domains: (1) the imaging of 180° antiferromagnetic domains in cobalt fluoride is performed using the inverse piezomagnetic effect: the action of a magnetic field while cooling and `memory' effects are investigated in this way, and (2) the spin density wave domains in chromium are observed using their associated, weak, charge density wave peaks: the importance of the surface effects to determine the domain type is evidenced.

A weak ferromagnetic phase is shown in pressed pellets of partially doped poly(3-methylthiophene) (P3MT) in the whole range from 1.8 to 300 K in magnetic measurements. Thermoremanence data have been used to estimate the suppression of this phase to be around 815 K. We also show that instead of the classical antiferromagnetism for the first-order interaction that gives weak ferromagnetism as a second-order effect, metamagnetic behavior is observed. X-band electron spin resonance (ESR) measurements and magnetization measurements allowed us to estimate that 8.1% of the total number of spins contributes to the weak ferromagnetism at room temperature. The doping level obtained from the ESR data is in good agreement with that estimated from electron dispersive spectroscopy measurements.

The magnetic susceptibility of Cr+0.2 at.% V and Cr+0.4 at.% V alloys (nominal concentrations) is found to show a sharp increase at the Neel temperature with increasing temperature and to obey a Curie-Weiss law in the paramagnetic phase up to 400 K, corresponding to a moment per V atom of about one Bohr magneton. The relation of these results to the behaviour of other physical properties of dilute CrV alloys is discussed.

Phosphate glasses containing CdFe ₂ O ₄ magnetic nanoparticles coated with SiO ₂ were successfully prepared by a melt-quenching methodology.