A low-temperature anomaly in dielectric properties of magnetite nanoparticles

The dielectric response of magnetic alkali borosilicate glasses containing single-domain magnetite nanoparticles was studied upon heating and cooling in magnetic fields from 0 to 10 Т in the temperature range from 5 to 100 K in the frequency range from 1 Hz to 160 kHz. An anomaly of the dielectric response was observed for the single-domain nanoparticles of magnetite in the temperature range of 15–50 K, position of which corresponds to the transition into the relaxor state observed in bulk material. A temperature hysteresis of this anomaly was found upon heating and cooling, which decreased as the observation frequency decreased.