Peculiarities of phase transitions in disordered perovskite-like crystals—PbMg_1/3 Nb_2/3 O₃ (PMN) and Na_1/2 Bi_1/2 TiO₃ (NBT) have been studied by neutron scattering. The strong quasielastic scattering (QES) related to ferroelectric critical fluctuations has been observed instead of expected inelastic scattering of soft phonon mode. The wavevector dependence of this diffuse scattering has been well described by Ornstein-Zernice formula. The correlation length temperature dependence resembling that of spin-glasses has obtained. The history dependent effects have been found by measurements in electric field in “field cooled” (FC) and “zero field cooled” regimes. Those effects as well as long-time relaxation of Bragg peaks intensity, observed below certain temperature, clearly indicate glass-like nature of low-temperature phase.

Using neutron reflectometry and resonant x-ray techniques we studied the magnetic proximity effect (MPE) in superlattices composed of superconducting ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_7$ and ferromagnetic-metallic ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_3$ or ferromagnetic-insulating ${\mathrm{LaMnO}}_{3+\delta }$. We find that the MPE strongly depends on the electronic state of the manganite layers, being pronounced for the ferromagnetic-metallic ${\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_3$ and almost absent for ferromagnetic-insulating ${\mathrm{LaMnO}}_{3+\delta }$. We also detail the change of the magnetic depth profile due to the MPE and provide evidence for its intrinsic nature.

Arrangement of chromatin in intact chicken erythrocyte nuclei was investigated by small angle neutron scattering. The scattering spectra have revealed that on the scales between 15 nm and 1.5 μm the ...

Direct evidence of the nonuniformly canted state of the spin-flop phase induced by a magnetic field applied to $\mathrm{F}\mathrm{e}/\mathrm{C}\mathrm{r}(100)$ superlattices is obtained by polarized neutron reflectometry. It is unambiguously demonstrated that the magnetization of the alternating Fe layers is twisted through the multilayer stack proving a stable noncollinear configuration. The maximal tilt at the end layers progressively reduces towards the center of the multilayer. The set of tilt angles is deduced from a model-free data evaluation employing the supermatrix routine. Spin-flip off-specular scattering is determined by the in-plane magnetization fluctuations and is fitted by a theoretical model of domains.

An effective method to probe local magnetostatic properties in a nanometric FePd antidot array F

The general equation for polarized neutron reflectivity is derived and presented in an invariant vector form that is independent of the selection of a specific coordinate system. Using this representation the reflectivity may easily and thoroughly be analyzed for arbitrary orientation of the sample, the incident beam polarization, and the direction of polarization analysis. It is shown that the complete information that can be extracted from experimental data by a detailed polarization analysis is given by the following quantities: the two complex eigenvalues of the reflectance matrix and a complex vector defining a direction that coincides with the direction of the magnetizations in a collinear magnetization arrangement, but depends on the momentum transfer in the general noncollinear case. A supermatrix formalism is developed and illustrated that allows us to calculate these parameters for multilayers with arbitrary mutual orientation of the magnetizations in individual layers. Our approach opens an alternative way to a complete and unambiguous characterization of artificial magnetic structures of high complexity.