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Dielectric and magnetic relaxation of single-crystal hexaferrite Ba0.3Pb0.7Fe12O19

Hexagonal barium hexaferrite Ba(Fe, Al)12O19 has been largely studied because of its wide range of important technological applications such as permanent magnets, magnetic-recording media, magneto-optical devices, microwave devices etc. [1, 2]. On the other hand, studies on lead-based PbFe12O19 have shown that it is ferromagnetic and ferroelectric at high temperatures [3]. Apparently, the dielectric, magnetic and optical properties of this material family can be highly influenced by lead-doping. Moreover, spin and charge of iron ions within the hexaferrite structure suggest there might a coupling between magnetic and dielectric excitations [4]. We present the study of frequency-dependent dielectric and magnetic response on single-crystalline lead-substituted hexaferrite Ba0.3Pb0.7Fe12O19 in the Hz-MHz frequency window at low temperatures. Our measurements show a temperature-dependent relaxation of both spins and charges. We discuss the dispersion of these relaxations and their origin in the context of magnetic domain walls. [1] U. Ozgur, et. al “Microwave ferrites, part 1: fundamental properties”, J Mater Sci-Mater Electron 20, 789–834 (2009). [2] R.C. Pullar, et.al “Hexagonal ferrites: a review of the synthesis, properties and applications of hexaferrite ceramics”, Prog Mater Sci 57, 1191–1334 (2012). [3]. Tan, G. L et. al “Ferroelectricity and Ferromagnetism of M‐Type Lead Hexaferrite”. Journal of the American Ceramic Society, 98(6), 1812-1817 (2015). [4] L. Alyabyeva et al., Proceedings of the 43rd International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THZ) (2018).

hexaferrite, birelaxor, ac magnetic susceptibility, domain wall, dispersion

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