XRD pattern for O nanopowder. The small features marked with stars are caused by minority phase. (a) XRD pattern for powder prepared by the sol-gel route. The small Cu peaks originate from the sample holder (b).
AFM image of ceramic . The scan size is .
EPR spectra of observed at 4.2 K in ceramic samples (a) and (b). The gain of the EPR spectrometer is same for all lines, except for which the gain is ten times higher.
Electron spin resonance lines A and B observed in (a) and the C line observed in (b). All spectra are measured with the same gain of the EPR spectrometer.
Temperature dependence of the resonance fields of the A and B lines in with (closed symbols) and (open symbols) and of the C line (triangles) observed in .
Magnetization of , scaled with (triangles), 0.06 (circles), and 0.25 (squares). The inset shows the temperature dependence of 1/M for the same samples in the field of 100 mT.
Temperature dependence of (closed symbols) and (open symbols) measured in the field of 100 mT for with , 0.10. The inset shows the plot of ln M vs 1/T for below 45 K.
Temperature dependence of (closed circles) and (open circles) for and the fit to the experimental data calculated with Eq. (2), (inset, solid line). The M(T) curve for is shown by triangles.
Critical behavior of the magnetic susceptibility of . The values of the critical exponents are: (left hand side) and (right hand side).
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