Intrinsic defects in multiferroic BiFeO₃ and their effect on magnetism

Authors

Tula R. Paudel, University of Nebraska-LincolnFollow
Sitaram S. Jaswal, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow

Date of this Version

2012

Citation

PHYSICAL REVIEW B 85, (2012) 104409(1-8). DOI:10.1103/PhysRevB.85.104409

Comments

Copyright © 2012 American Physical Society. Used by Permission.

Abstract

We investigate the energetics of the intrinsic defects in bulk multiferroic BiFeO₃ and explore their implication for magnetization using a first-principles approach based on density functional theory. We find that the dominant defects in oxidizing (oxygen-rich) conditions are Bi and Fe vacancies and in reducing (oxygen-poor) conditions are O and Bi vacancies. The calculated carrier concentration shows that the BiFeO₃ grown in oxidizing conditions has p-type conductivity. The conductivity decreases with oxygen partial pressure, and the material becomes insulating with a tendency for n-type conductivity. We find that the Bi and Fe vacancies produce a magnetic moment of ∼1μ_B and 5μ_B per vacancy, respectively, for p-type BiFeO₃ and none for insulating BiFeO₃. O vacancies do not introduce any moment for both p-type and insulating BiFeO₃. Calculated magnetic moments due to intrinsic defects are consistent with those reported experimentally for bulk BiFeO₃.