中国物理B ›› 2008, Vol. 17 ›› Issue (5): 1874-1880.doi: 10.1088/1674-1056/17/5/055

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Electronic structures and magnetoelectric properties of tetragonal BaFeO3: an ab initio density functional theory study

冯宏剑, 刘发民   

  1. School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
  • 收稿日期:2007-08-08 修回日期:2007-11-12 出版日期:2008-05-20 发布日期:2008-05-20
  • 基金资助:
    Project supported by the Aeronautical Science Foundation of China (Grant No 2003ZG51069).

Electronic structures and magnetoelectric properties of tetragonal BaFeO3: an ab initio density functional theory study

Feng Hong-Jian(冯宏剑)† and Liu Fa-Min(刘发民)   

  1. School of Science, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
  • Received:2007-08-08 Revised:2007-11-12 Online:2008-05-20 Published:2008-05-20
  • Supported by:
    Project supported by the Aeronautical Science Foundation of China (Grant No 2003ZG51069).

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摘要： First-principles calculations have been performed to investigate the ground state electronic properties of BaFeO3 (BFO). Local spin density approximation (LSDA) plus U (LSDA+U) treatment modified the metallic behaviour to insulated one with a band gap of 4.12eV. The spontaneous polarization was found to be 89.3\muC/cm2 with Berry phase scheme in terms of the modern theory of polarization. Fe-3d eg were split into two singlet states (dz2 and d x2-y2}), and Fe-3d t2g were split into one doublet states(dxz and dyz) and one singlet states(dxy) after Fe and O displaced along the c axis. Meanwhile the occupation numbers of dz2, dyz, dxz and OT pz (on the top of Fe) were increased at the expense of those in xy plane. Our results showed that it was the sensitivity of hybridization to ferroelectric distortions, not just the total change of hybridization, that produced the possibility of ferroelectricity. Moreover, the increasing occupation numbers of OT pz and Fe dz2 favoured the 180o coupling between Fe-3d eg and Fe-3d t2g, leading to ferromagnetic ordering, which has been confirmed by the increase of magnetic moment by 0.13μB per formula unit in the polarized direction. Hence, the magnetization can be altered by the reversal of external electric field.

关键词: multiferroic, density functional theory, density of states, band structures

Abstract: First-principles calculations have been performed to investigate the ground state electronic properties of BaFeO3 (BFO). Local spin density approximation (LSDA) plus U (LSDA+U) treatment modified the metallic behaviour to insulated one with a band gap of 4.12eV. The spontaneous polarization was found to be 89.3$\mu$C/cm2 with Berry phase scheme in terms of the modern theory of polarization. Fe-3d eg were split into two singlet states (dz2 and dx2-y2}), and Fe-3d t2g were split into one doublet states(dxz and dyz) and one singlet states(dxy) after Fe and O displaced along the c axis. Meanwhile the occupation numbers of dz2, dxz, dyz and OT pz (on the top of Fe) were increased at the expense of those in xy plane. Our results showed that it was the sensitivity of hybridization to ferroelectric distortions, not just the total change of hybridization, that produced the possibility of ferroelectricity. Moreover, the increasing occupation numbers of OT pz and Fe dz2 favoured the 180o coupling between Fe-3d eg and Fe-3d t2g, leading to ferromagnetic ordering, which has been confirmed by the increase of magnetic moment by 0.13$\mu$B per formula unit in the polarized direction. Hence, the magnetization can be altered by the reversal of external electric field.

Key words: multiferroic, density functional theory, density of states, band structures

中图分类号:  (Density functional theory, local density approximation, gradient and other corrections)

  • 71.15.Mb
71.20.Ps (Other inorganic compounds) 72.20.My (Galvanomagnetic and other magnetotransport effects) 75.30.Cr (Saturation moments and magnetic susceptibilities) 77.22.Ej (Polarization and depolarization) 77.80.-e (Ferroelectricity and antiferroelectricity)