Temperature dependence of the static dc magnetic susceptibility of PFN powder measured by a SQUID magnetometer at . The drop below is characteristic for the onset of antiferromagnetism. The insert shows the temperature dependence of the magnetic susceptibility around the ferroelectric transition temperature .
(Color online) -band EPR spectra of polycrystalline PFN at different temperatures. The solid lines correspond to theoretical fits to a model of thermally fluctuating superparamagnetic clusters, as described in Refs. 20 and 21. The nanocluster size amounts to at room temperature.
(Color online) -band EPR spectra of polycrystalline PFN between 10 and . The temperature is increased from up.
Shift of the center of the gravity of the -band EPR spectra as a function of temperature.
The widths of the -band (full dots) and -band (empty dots) EPR spectra as a function of temperature.
(Color online) Magnetic field dependence of the magnetization at various temperatures. The nonlinear behavior of the magnetization vs magnetic field plots persists to , demonstrating the existence of weak ferromagnetism.
(Color online) The “slim” magnetization hysteresis curves of PFN at different temperatures.
(Color online) Temperature dependence of the remanent magnetization in PFN powder. The insert shows the difference between the FC and ZFC static magnetic susceptibilities above , demonstrating the existence of a nonequilibrium state, which disappears in the antiferromagnetic phase.
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