Magnetic state of nanocrystals of Zn-substituted magnetite

A system of ultrasmall nanocrystals of zinc-substituted magnetite has been synthesized by chemical condensation. Indications of a transition of the particles into a superparamagnetic state have been found by two methods—1) measurements of the temperature dependence of the magnetization in the temperature interval 4.2–250K for fixed values of the external magnetic field from 10Oeto2kOe and 2) the major hysteresis loop at 300K. The dependence of the blocking temperature on the magnetic field strength is obtained.