Lightening the load: Permanent magnets are generally produced from solid metals or alloys. Less dense compositions involving lighter elements tend to demagnetize well below room temperature or under modest applied external fields. Perlepe et al. now report that chemical reduction of a low-density chromium-pyrazine network produces a magnet that remains stable above 200°C and resists demagnetization with 7500-oersted coercivity at room temperature. The straightforward synthetic route to the material shows promise for broad exploration of potential applications. Science , this issue p. 587

Magnetochiral Dichroism of chiral mononuclear lanthanoid complexes is for the first time detected by X-ray absorption measurements on single crystals of Holmium oxydiacetate, at the Ho L₃-edge. The effect is of opposite sign for the two enantiomers.

The crystal structure and magnetic properties of Co₃B₂O₆ single crystals are studied. Orthorhombic symmetry with space group Pnnm is detected at room temperature. The measurements of static magnetization and dynamic magnetic susceptibility reveal two magnetic anomalies at T ₁ = 33 K and T ₂ = 10 K and an easy-axis magnetic anisotropy. The effective magnetic moment indicates a high-spin state of the Co²⁺ ion. A spin-flop transition is found at low temperatures and H _sf = 23 kOe. EXAFS spectra of the K-edge absorption of Co are recorded at various temperatures, the temperature-induced changes in the parameters of the local environment of cobalt are analyzed, and the effective Co-Co and Co-O distances are determined. The magnetic interactions in the crystal are analyzed in terms of an indirect coupling model.

The polarizing spectroscopy techniques in visible range optics have been used since the beginning of the 20th century to study the anisotropy of crystals based on birefringence and optical activity phenomena. On the other hand, the phenomenon of X-ray optical activity has been demonstrated only relatively recently. It is a selective probe for the element-specific properties of individual atoms in non-centrosymmetric materials. We report the X-ray Natural Circular Dichroism (XNCD) imaging technique which enables spatially resolved mapping of X-ray optical activity in non-centrosymmetric materials. As an example, we present the results of combining micro-focusing X-ray optics with circularly polarized hard X-rays to make a map of enantiomorphous twinning in a multiferroic SmFe${}_3$(BO${}_3$)${}_4$ crystal. Our results demonstrate the utility and potential of polarization-contrast imaging with XNCD as a sensitive technique for multiferroic crystals where the local enantiomorphous properties are especially important. In perspective, this brings a novel high-performance method for the characterization of structural changes associated with phase transitions and identification of the size and spatial distribution of twin domains.