Charge, orbital and spin ordering in multiferroic BiMn2O5: density functional theory calculations

Area of Science:

• Condensed matter physics
• Materials science
• Computational materials science

Background:

• Multiferroic materials exhibit complex interplay between charge, orbital, and spin degrees of freedom.
• Understanding these interactions is crucial for designing novel electronic and magnetic devices.

Purpose of the Study:

• To investigate the charge, orbital, and spin ordering in multiferroic BiMn(2)O(5).
• To elucidate the relationship between charge ordering and ferroelectric polarization in this material.

Main Methods:

• Utilized the full-potential linearized augmented plane-wave (FPLAPW) method.
• Employed both generalized gradient approximation (GGA) and GGA plus one-site Coulomb interaction (GGA+U) for exchange-correlation functional calculations.
• Analyzed Born effective charges to understand polarization mechanisms.

Main Results:

• BiMn(2)O(5) is stable in a ferrimagnetic state with a band gap of approximately 1.23 eV.
• Identified two distinct manganese ions, Mn1 (Mn(4+)) and Mn2 (Mn(3+)), with different ionicities and magnetic moments.
• Observed significant differences in e(g) minority occupancies, providing direct evidence of charge ordering.
• Confirmed that partial ferroelectric polarization originates from this charge ordering.

Conclusions:

• Charge ordering in BiMn(2)O(5) is definitively established through theoretical calculations.
• The findings support the link between charge ordering and ferroelectric polarization, consistent with existing literature.
• This work provides a fundamental understanding of the electronic and magnetic properties of BiMn(2)O(5).