γ-BaFeO: a fresh playground for room temperature multiferroicity.

Multiferroics, showing the coexistence of two or more ferroic orderings at room temperature, could harness a revolution in multifunctional devices. However, most of the multiferroic compounds known to date are not magnetically and electrically ordered at ambient conditions, so the discovery of new materials is pivotal to allow the development of the field. In this work, we show that BaFeO is a previously unrecognized room temperature multiferroic.

Centrosymmetry Breaking and Ferroelectricity Driven by Short-Range Magnetic Order in the Quadruple Perovskite (YMn)MnO.

By means of single-crystal X-ray diffraction, we give direct crystallographic evidence of a centrosymmetry breaking below = 200 K, concomitant with the onset of a commensurate structural modulation in the quadruple perovskite YMnMnO. This result, which explains the anomalously large thermal coefficient of the Y ion in previously reported structural models, is attributed to the small size of the Y ion, which causes its underbonding within the dodecahedral coordination polyhedron. The present data are consistent with a commensurate superstructure described by an I-centered pseudo-orthorhombic cell with polar symmetry and ≈ √2 = 10.

Singling out the effect of quenched disorder in the phase diagram of cuprates.

We investigate the specific influence of structural disorder on the suppression of antiferromagnetic order and on the emergence of cuprate superconductivity. We single out pure disorder, by focusing on a series of [Formula: see text] samples at fixed oxygen content y   =  0.35, in the range [Formula: see text].

Synthesis and crystal structure of 4-fluoro-benzyl-ammonium di-hydrogen phosphate, [FCHCHNH]HPO.

The asymmetric unit of the title salt, [-FCHCHNH]·HPO, contains one 4-fluoro-benzyl-ammonium cation and one di-hydrogen phosphate anion. In the crystal, the HPO anions are linked by O-H⋯O hydrogen bonds to build corrugated layers extending parallel to the plane. The FCHCHNH cations lie between these anionic layers to maximize the electrostatic inter-actions and are linked to the HPO anions through N-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular network.

Crystal Structure and Ferroelectric Properties of ε-GaO Films Grown on (0001)-Sapphire.

The crystal structure and ferroelectric properties of ε-GaO deposited by low-temperature MOCVD on (0001)-sapphire were investigated by single-crystal X-ray diffraction and the dynamic hysteresis measurement technique. A thorough investigation of this relatively unknown polymorph of GaO showed that it is composed of layers of both octahedrally and tetrahedrally coordinated Ga sites, which appear to be occupied with a 66% probability. The refinement of the crystal structure in the noncentrosymmetric space group P6mc pointed out the presence of uncompensated electrical dipoles suggesting ferroelectric properties, which were finally demonstrated by independent measurements of the ferroelectric hysteresis.