Ferroelectricity and Ferromagnetism of M‐Type Lead Hexaferrite

Abstract

Polarization and related properties in the M‐type lead hexaferrite ( PbFe 12 O 19 ) are reported for the first time. The remnant polarization of PbFe 12 O 19 exhibits a maximum value of 104 μC/cm 2 , as well as large spontaneous polarization at room temperature. Annealing of PbFe 12 O 19 in oxygen plays a key role in the saturation of its polarization hysteresis loop because it greatly enhances the ceramic's electric resistance. Two current peaks in the I–V curve reveal a polarization switch, providing effective evidence for the ferroelectricity of PbFe 12 O 19 . Its temperature‐dependent dielectric constant undergoes colossal change in the vicinity of two temperatures (322°C and 518°C), which are assigned to the transitions from ferro‐ to antiferro‐ and antiferro‐ to paraelectric phases, respectively. The plots of logarithm of (1/ε–1/ε m ) as a function of logarithm of ( T – T m ) obey a modified Curie–Weiss law, verifying the relaxor ferroelectric characterization of PbFe 12 O 19 . The ceramic also exhibits a strong magnetic hysteresis loop. These combined functional responses of ferroelectricity and ferromagnetism in PbFe 12 O 19 ceramic present an opportunity to create electric devices that actively couple the magnetic and ferroelectric orders.