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We report the structural and magnetic ground state properties of the monoclinic compound barium iridium oxide Ba4Ir3O10 using a combination of resonant x-ray scattering, magnetometry, and thermodynamic techniques. Magnetic susceptibility exhibits a pronounced antiferromagnetic transition at TN≈25 K, a weaker anomaly at TS≈142 K, and strong magnetic anisotropy at all temperatures. Resonant elastic x-ray scattering experiments reveal a second order structural phase transition at TS and a magnetic transition at TN. Both structural and magnetic superlattice peaks are observed at L = half integer values. The magnetization anomaly at TS implies the presence of magnetoelastic coupling, which conceivably facilitates the symmetry lowering. Mean field critical scattering is observed above TS. The magnetic structure of the antiferromagnetic ground state is discussed based on the measured magnetic superlattice peak intensity. Our study not only presents essential information for understanding the intertwined structural and magnetic properties in Ba4Ir3O10 but also highlights the necessary ingredients for exploring novel ground states with octahedra trimers.

The advent of long-range magnetic order in non-centrosymmetric compounds hasstimulated interest in the possibility of exotic spin transport phenomena andtopologically protected spin textures for applications in next-generationspintronics. This work reports a novel wurtzite-structure polar magnetic metal,identified as AA'-stacked (Fe0.5Co0.5)5-xGeTe2, which exhibits a Neel-typeskyrmion lattice as well as a Rashba-Edelstein effect at room temperature.Atomic resolution imaging of the structure reveals a structural transition as afunction of Co-substitution, leading to the polar phase at 50% Co. Thisdiscovery reveals an unprecedented layered polar magnetic system forinvestigating intriguing spin topologies and ushers in a promising newframework for spintronics.

Spin nematics break spin-rotational symmetry while maintaining time-reversal symmetry, analogous to liquid crystal nematics that break spatial rotational symmetry while maintaining translational symmetry. Although several candidate spin nematics have been proposed, the identification and characterization of such a state remain challenging because the spin-nematic order parameter does not couple directly to experimental probes. KFe_{0.8}Ag_{1.2}Te_{2} (K_{5}Fe_{4}Ag_{6}Te_{10}, KFAT) is a local-moment magnet consisting of well-separated 2×2 Fe clusters, and in its ground state the clusters order magnetically, breaking both spin-rotational and time-reversal symmetries. Using uniform magnetic susceptibility and neutron scattering measurements, we find a small strain induces sizable spin anisotropy in the paramagnetic state of KFAT, manifestly breaking spin-rotational symmetry while retaining time-reversal symmetry, resulting in a strain-induced spin-nematic state in which the 2×2 clusters act as the spin analog of molecules in a liquid crystal nematic. The strain-induced spin anisotropy in KFAT allows us to probe its nematic susceptibility, revealing a divergentlike increase upon cooling, indicating the ordered ground state is driven by a spin-orbital entangled nematic order parameter.

Ga2SeTe2 belongs to a family of materials with large intrinsic vacancyconcentrations that are being actively studied due to their potential fordiverse applications that include thermoelectrics and phase-change memory. Inthis article, the Ga2SeTe2 structure is investigated via synchrotron x-raydiffraction, electron microscopy, and x-ray absorption experiments. Diffractionand microscopy measurements showed that the extent of vacancy ordering inGa2SeTe2 is highly dependent on thermal annealing. It is posited thatstoichiometric vacancies play a role in local atomic distortions in Ga2SeTe2(based on the fine structure signals in the collected x-ray absorptionspectra). The effect of vacancy ordering on Ga2SeTe2 material properties isalso examined through band gap and Hall effect measurements, which reveal thatthe Ga2SeTe2 band gap redshifts by ~0.05 eV as the vacancies order andaccompanied by gains in charge carrier mobility. The results serve as anencouraging example of altering material properties via intrinsic structuralrearrangement as opposed to extrinsic means such as doping.