The structural motif of the Cu2OSeO3 crystal, constructed according to the data in Ref. 3 at T = 10 K. The SeO3 complexes are not shown.
Temperature dependence of the reflectance spectra of the Cu2OSeO3crystal. Starting at 70 K the spectra are shifted to the region of increased reflection coefficient with a step of 0.1.
Approximation of the reflection spectrum of Cu2OSeO3 at 10 K; circles show experimental values, the solid line shows the calculated values.
The scheme for obtaining a differential Raman spectrum (T = 65 K) to highlight the lines of A- and E-symmetry. The numbers denote the following spectra: 1 – in the parallel polarization, 2 – in the crossed polarization, 3 – calculated spectrum of A-symmetry modes, 4 – the differential spectrum. The arrows indicate the position of E-modes. Explanation is in the text.
Temperature dependence of the frequencies of bands in the Raman spectrum of Cu2OSeO3: circles denote bands related to the F- and E-symmetry modes, black squares denote bands related to the A-symmetry modes.
Temperature dependence of the frequencies of bands in the IR reflectance spectrum of Cu2OSeO3: black symbols denote the modes manifesting “anomalous” behavior below the temperature of magnetic ordering.
Comparison of the temperature evolution of some sections of Raman spectra (upper panel) and the frequency dependence of the imaginary portion of the dielectric function ɛ″, obtained from the approximation of IR reflectance spectra (lower panel) in the area of “anomalous” modes.
Temperature behavior of the frequencies (upper panel), full widths at half maximum (middle panel), and areas (lower panel) of “anomalous” bands in the Raman spectrum of Cu2OSeO3. The solid lines are drawn for clarity. Black squares show the behavior of the area of the band at 250 cm–1 in the IR absorption spectrum in relative units. In the bottom right panel the solid line shows the behavior of the half-sum of the areas of bands at 255 and 260 cm−1.
Temperature behavior of frequencies (a) and the reduced areas (b) of the bands in the Raman (circles) and IR (black squares) spectra of Cu2OSeO3.The solid curve in the top panel (b) corresponds to the behavior of the order parameter;8 in the rest of the plots the solid curves are drawn for clarity.
Field dependence of the IR reflectance portion of the spectrum (a) and the calculated imaginary portion of the dielectric function ɛ″ (b) of the Cu2OSeO3crystal.
The dependence of frequencies (left panel) and areas (right panel) of Lorentzians approximating the imaginary portion of the dielectric function in the areas of “anomalous” modes on the external magnetic field. The solid lines are drawn for clarity.
Temperature dependence of the multiparticle continuum (shaded area) in the Raman scattering spectra of Cu2OSeO3 in the parallel polarization.
Symmetry and frequencies of vibrational modes observed in Raman scattering and IR absorption spectra at 10 K.
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