Noncollinear Magnetic Structures in the Chiral Antiperovskite β-FeSeO.

We present the magnetic properties of the chiral, polar, and possibly magnetoelectric antiperovskite β-FeSeO as derived from magnetization and specific-heat measurements as well as from powder neutron diffraction and Mössbauer experiments. Our macroscopic data unambiguously reveal two magnetic phase transitions at ≈ 103 K and ≈ 78 K, while Rietveld analysis of neutron powder diffraction data reveals a noncollinear antiferromagnetic structure featuring magnetic moments in the - plane of the trigonal structure and a ferromagnetic moment along . The latter is allowed by symmetry between and , weakly visible in the magnetization data yet unresolvable microscopically.

Adherence of the rotating vortex lattice in the noncentrosymmetric superconductor RuBto the London model.

The noncentrosymmetric superconductor RuBhas in previous studies demonstrated remarkably unusual behaviour in its vortex lattice (VL), where the nearest neighbour directions of the vortices dissociate from the crystal lattice and instead show a complex field-history dependence, and the VL rotates as the field is changed. In this study, we look at the VL form factor of RuBduring this field-history dependence, to check for deviations from established models, such as the London model. We find that the data is well described by the anisotropic London model, which is in accordance with theoretical predictions that the alterations to the structure of the vortices due to broken inversion symmetry should be small.

Crystal Growth, Structure, and Noninteracting Quantum Spins in Cyanochroite, KCu(SO)·6HO.

The rare mineral cyanochroite, KCu(SO)·6HO, features isolated Cu ions in distorted octahedral coordination, linked via a hydrogen-bond network. We have grown single crystals of cyanochroite as large as ∼0.5 cm and investigated structural and magnetic aspects of this material.

Stripe-magnetic order in the triangular-lattice antiferromagnet KCeS.

Yb- and Ce-based delafossites were recently identified as effective spin-1/2 antiferromagnets on the triangular lattice. Several Yb-based systems, such as NaYbO, NaYbS, and NaYbSe, exhibit no long-range order down to the lowest measured temperatures and therefore serve as putative candidates for the realization of a quantum spin liquid. However, their isostructural Ce-based counterpart KCeSexhibits magnetic order below= 400 mK, which was so far identified only in thermodynamic measurements.