Abstract

We revisit the magnetic properties of the hexagonal ferrite PbFe12-xGaxO19. Recent experiments have reported puzzling dependences of the ordering temperature and the saturation magnetization on the Ga concentration x. To explain these observations, we perform large-scale Monte Carlo simulations, focusing on the effects of an unequal distribution of the Ga impurities over the five distinct Fe sublattices. Ab initio density-functional calculations predict that the Ga ions preferably occupy the 12k sublattice and (to a lesser extent) the 2a sublattice. We incorporate this insight into a nonuniform model of the Ga distribution. Monte Carlo simulations using this model lead to an excellent agreement between the theoretical and experimental values of the ordering temperature and saturation magnetization, indicating that the unequal distribution of the Ga impurities is the main reason for the unusual magnetic properties of PbFe12-xGaxO19. We also compute the temperature and concentration dependences of the sublattice magnetizations, and we study the character of the zero-temperature transition that takes place when the ordering temperature is tuned to zero.

Department(s)

Physics

International Standard Serial Number (ISSN)

2469-9969; 2469-9950

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2024 American Physical Society, All rights reserved.

Publication Date

01 Jul 2024

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