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A new magnetic phase is reported in the chiral magnet, Cu2OSeO3, which is predicted to affect its physical properties.

Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet Fe 1−x Co x Si with x = 0.3 reveal a pronounced effect of the magnetic history and cooling rates on the magnetic phase diagram. The extracted phase diagrams are qualitatively different for zero and field cooling and reveal a metastable skyrmion lattice phase outside the A phase for the latter case. These thermodynamically metastable skyrmion lattice correlations coexist with the conical phase and can be enhanced by increasing the cooling rate. They appear in a wide region of the phase diagram at temperatures below the A phase but also at fields considerably smaller or higher than the fields required to stabilize the A phase.

Magnetic skyrmions are nanosized topologically protected spin textures with particlelike properties. They can form lattices perpendicular to the magnetic field, and the orientation of these skyrmion lattices with respect to the crystallographic lattice is governed by spin-orbit coupling. By performing small-angle neutron scattering measurements, we investigate the coupling between the crystallographic and skyrmion lattices in both Cu 2 OSeO 3 and the archetype chiral magnet MnSi. The results reveal that the orientation of the skyrmion lattice is primarily determined by the magnetic field direction with respect to the crystallographic lattice. In addition, it is also influenced by the magnetic history of the sample, which can induce metastable lattices. Kinetic measurements show that these metastable skyrmion lattices may or may not relax to their equilibrium positions under macroscopic relaxation times. Furthermore, multidomain lattices may form when two or more equivalent crystallographic directions are favored by spin-orbit coupling and oriented perpendicular to the magnetic field.

Bonding characterization, density measurement, and thermal diffusivity studies of amorphous silicon carbon nitride and boron carbon nitride thin filmsThe objective of this study is to develop improved procedures for characterizing amorphous carbon films. Raman spectroscopy is used to characterize amorphous carbon thin films grown by pulsed laser deposition at temperatures between 293 and 873 K. The amount of bond-angle disorder is shown to decrease with increasing substrate temperature. However, a shift of the Raman D peak to higher wave numbers is not observed to coincide with the presumed decrease in sp 3 bonding as the deposition temperature increases. The graphitic domain size is shown to initially decrease, pass through a minimum, and then increase as temperature increases. Mass densities, measured independently by x-ray specular reflectometry, are seen to decrease from a maximum of 2.4 g/cm Ϫ3 as deposition temperature increases. The trend in the observed density measurements correlates well with the Raman spectroscopy data. The importance of x-ray specular reflectometry as part of a strategy to completely characterize amorphous carbon films is discussed in terms of these data.