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The electronic ground state and the electric conductivity of W-type hexagonal ferrite BaFe18O27 are investigated in the generalized gradient approximation (GGA) as well as the GGA plus Hubbard U(GGA+U) scheme. The ionic relaxation calculation of the experimental crystal structure shows that oxygen ions at 6h site in the BaO layer move away from the surface position in the unit cell, resulting in a structural distortion. The magnetic moment of the cell is calculated to be 28 B/f.u., in agreement with previous experimental results. By taking account of electronic band structure and crystal ionic configuration it is found that the material is a weak half-metal and the effective mass of conduction electrons along the c axis is much heavier than that perpendicular to this axis. Fe ions on octahedral 6 g sites and O ions around them of the spinel block form a conductive layer. Therefore the electric conductivity perpendicular to the c axis is much greater than that parallel to the c axis.
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Keywords:
- first-principles /
- W-type hexagonal ferrite /
- electronic structure /
- electric conductivity
[1] Li Z W, Lin G Q, Wu Y P, Kong L B 2009 J. Phys. D 42 095007
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[21] [22] [23] Ŝimŝa Z, Zalesskij, Zvěta K 1966 Phys. Stat. Sol. 14 485
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[26] Collomb A, Wolfers P, Obradors X 1986 J. Magn. Magn.Mater. 62 57
[27] [28] Zhou F, Ceder G 2010 Phys. Rev. B 81 205113
[29] -
[1] Li Z W, Lin G Q, Wu Y P, Kong L B 2009 J. Phys. D 42 095007
[2] [3] Vmit zgr, Yahya Alivov, Hadis Morko 2009 J. Mater. Sci: Mater Electron 20 789
[4] [5] Harris V G, Geiler A, Chen Y J, Yoon S D, Wu M Z, Yang A, Chen Z H, He P, Parimi P V, Zuo X, Patton C E, Abe M, Acher O, Vittoria C 2009 J. Magn. Magn. Mater. 321 2035
[6] Novk P, Rusz J 2005 Phys. Rev. B 71 184433
[7] [8] [9] Fang C M, Kools F, Metselaar R, With G and Groot R A 2003 J. Phys. C 15 6229
[10] [11] Knžek K, Novk P, Kpferling M 2006 Phys. Rev. B 73 153103
[12] Braun P B 1957 Philips. Res. Rep. 12 491
[13] [14] Gorter E W 1957 Proc. IEE 104 B (suppl.) 255
[15] [16] Kresse G, Furthmller J 1996 Phys. Rev. B 54 11169
[17] [18] Perdew J P, Burke K, Ernzerhof M 1996 Phys. Rev. Lett. 77 3865
[19] [20] Dudarev S L, Botton G A, Savrasov S Y, Humphreys C J, Sutton A P 1998 Phys. Rev. B 57 1505
[21] [22] [23] Ŝimŝa Z, Zalesskij, Zvěta K 1966 Phys. Stat. Sol. 14 485
[24] [25] Mattsson A E, Armiento R, Schultz P A, Mattsson T R 2006 Phys. Rev. B 73 195123; Paier J, Marsman M 2006 J. Chem. Phys. 124 154709
[26] Collomb A, Wolfers P, Obradors X 1986 J. Magn. Magn.Mater. 62 57
[27] [28] Zhou F, Ceder G 2010 Phys. Rev. B 81 205113
[29]
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