Magnetic properties of nanocomposites based on opal matrices with embedded ferrite-spinel nanoparticles

• Magnetic properties of nanocomposites crystals have been studied.
• The crystals are based on opal matrices with nanoparticles of ferrite-spinels.
• The magnetic phase is ordered ferrimagnetically and superparamagnetically partially.
• The coercive field of the crystals sharply increases at cryogenic temperatures.
• The hysteresis loop has a place even at low times of impregnation.

Magnetic properties of nanocomposites based on opal matrices with ferrite-spinel nanoparticles embedded have been investigated in temperature range from 2 to 300 K. The magnetization curves and hysteresis loops as well as the temperature dependence of magnetic moment and the temperature and frequency dependences of AC susceptibility have been measured. The results of magnetic measurements are compared to X-ray analysis and electron microscopy investigations.