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基于密度泛函理论的平面波超软赝势方法模拟计算了金红石相TiO2的四种本征缺陷(氧空位、钛空位、钛间隙缺陷、氧间隙缺陷)和两种复合缺陷(氧空位与氧间隙复合缺陷、钛空位与钛间隙复合缺陷)的铁磁特性.结合态密度、电子分布及晶体结构变化分析可知,四种本征缺陷均会在系统内引入缺陷态.氧空位、钛间隙缺陷使费米面升高,引起自旋极化,引入磁矩分别为1.62 B与3.91 B;钛空位的缺陷态处于价带顶,使费米面进入价带,表现出明显的p型半导体特性,引入磁矩约为2.47 B;氧间隙缺陷引入缺陷态但仍然处于自旋对称状态,费米面略微下降;氧空位与氧间隙复合缺陷使费米面上升的程度比单个氧空位时大,模拟的超晶胞保持了氧空位的铁磁特性,大小为1.63 B;钛空位与钛间隙复合缺陷以反铁磁方式耦合,但超晶胞仍具有一定的铁磁特性.The TiO2 based diluted magnetic semiconductors (DMSs) have aroused the considerable interest as one of the promising candidates for the spintronic devices accommodating both charge and spin of electrons in a single substance. Unfortunately, however, throughout most of the published papers, the question how to clearly elucidate the role of defects which may be played in the experimentally observed room temperature ferromagnetism (RTFM) remains open, especially after a new concept of d0 ferromagnetism. In such a case, to further understand this issue and also to explore the origin of the RTFM in rutile TiO2, we here first perform a first principles calculation on the magnetic properties of the intrinsic defects, namely oxygen vacancy (VO), Ti vacancy (VTi), Ti interstitial (Tiin), oxygen interstitial (Oin) and two complex defects of VO+Oin and VTi+Tiin. Combining the density functional theory and the Perdew-Burke-Ernzerhof functional of the generalized gradient approximation, we calculate various model structures of rutile TiO2 constituted by 48-atom 222 supercell. The cutoff energies in these calculations of the planewave basis are all set to be 340 eV and the Monkhorst-Pack scheme k points are set to be 334 for an irreducible Brillouin zone. The convergence threshold for self-consistent field iteration is 0.145510-6 eV/atom. Structural relaxation is taken into account in each of all calculations. It is found that each defect we created in the structure leads to a lattice expansion and that the positive value for spin up and the negative value for spin down of the density of states (DOS) of the structure without defect are symmetric, suggesting that the perfect rutile TiO2 lattice is nonferromagnetic. For the system with one VO, the total energy of the spin-polarized system is 200 meV lower than that of the non-spin-polarized system, which indicates ferromagnetic behavior in this system. The defect brings in an impurity state near Fermi level located at about 0.71.0 eV down below the conduction band, resulting in an excess of spin up over spin down for the presences of the two localized electrons left by the vacancy. At this point the supercell bears a magnetic moment of about 1.62 B. In contrast, VTi also brings in an impurity state near Fermi level but above the valence band, which reveals a p-type characteristic semiconductor nature. Since a lower total energy requires more spin-up electrons, the asymmetric DOS induces a magnetic moment of 2.47 B. When a neutral Ti occupies an interstitial lattice site, the system requires it to be oxidized into a Ti3+ ion to increase the stabilization of the system. The three delocalized electrons tend to occupy the 3d or 4s orbital of the neighbor Ti4+ ions and then have strong exchange interactions with the 2p electrons of the local O atom. This can distort octahedral symmetry and give rise to a ferromagnetic moment of 3.91 B. Oin defect in the supercell is extremely unstable. It can easily be reduced and escape from the host in terms of an oxygen molecule so that the system is in a manner similar to the perfect lattice, showing no ferromagnetism. It is interesting to note that the properties of the system with the complex defect of one VO and Oin are similar to that of the structure with one VO and the magnetic moment of this system is 1.63 B. For the Ticom complex defect, our results point out the fact that the magnetic properties of the supercell are related to the distance between VTi and Tiin. The spin up and spin down states are symmetric when they are close to each other, while, in addition to some ferromagnetic behavior, the system mainly exhibits antiferromagnetism when the distance increases.
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Keywords:
- first-principles /
- intrinsic defect /
- density of states /
- magnetization
[1] Dietl T, Ohno H, Matsukura F, Cibert J, Ferrand D 2000 Science 287 1019
[2] Matsumoto Y, Murakami M, Shono T, Fukumura T, Kawasaki M, Ahmet P, Chikyow T, Koshihara S, Koinuma H 2001 Science 291 854
[3] Higgins J S, Shinde S R, Ogale S B, Venkatesan T, Greene R L 2004 Phys. Rev. B 69 073201
[4] Toyosaki H, Fukumura T, Yamada Y, Nakajima K, Chikyow T, Hasegawa T, Koinuma H, Kawasaki M 2004 Nat. Mater. 3 221
[5] Chambers S A, Wang C M, Thevuthasan S, Droubay T, Mccready D E, Lea A S, Shutthanandan V, Windisch C F 2002 Thin Solid Films 418 197
[6] Hong N H 2006 J. Magn. Magn. Mater. 303 338
[7] Paul S, Choudhury B, Choudhury A 2014 J. Alloy. Compd. 601 201
[8] Kim D H, Yang J S, Kim Y S, Kim D W, Noh T W, Bu S D, Kim Y W, Park Y D, Pearton S J, Jo Y, Park J G 2003 Appl. Phys. Lett. 83 4574
[9] Kang S H, Quynh H N T, Yoon S G, Kim E T, Lee Z, Radmilovic V 2007 Appl. Phys. Lett. 90 102504
[10] Shutthanandan V, Thevuthasan S, Heald S M, Droubay T, Engelhard M H, Kaspar T C, Mccready D E, Saraf L, Chambers S A, Mun B S, Hamdan N, Nachimuthu P, Taylor B, Sears R P, Sinkovic B 2004 Appl. Phys. Lett. 84 4466
[11] Griffin K A, Pakhomov A B, Wang C M, Heald S M, Krishnan K M 2005 Phys. Rev. Lett. 94 157204
[12] Santara B, Pal B, Giri P K 2011 J. Appl. Phys. 110 114322
[13] Pereira L C J, Nunes M R, Monteiro O C, Silvestre A J 2008 Appl. Phys. Lett. 93 222502
[14] Stausholm-Møller J, Kristoffersen H H, Hinnemann B, Madsen G K H, Hammer B 2010 J. Chem. Phys. 133 144708
[15] Shi L B, Wang Y P 2016 J. Magn. Magn. Mater. 405 1
[16] Zarhri Z, Houmad M, Ziat Y, El Rhazouani O, Slassi A, Benyoussef A, El Kenz A 2016 J. Magn. Magn. Mater. 406 212
[17] Kim D, Hong J, Park Y R, Kim K J 2009 J. Phys.:Condens. Matter 21 195405
[18] Máca F, Kudrnovsky J, Drchal V, Bouzerar G 2008 Appl. Phys. Lett. 92 212503
[19] Yang K, Dai Y, Huang B, Feng Y P 2010 Phys. Rev. B 81 033202
[20] Iddir H, Ğt S, Zapol P, Browning N D 2007 Phys. Rev. B 75 073203
[21] Na Phattalung S, Smith M F, Kim K, Du M H, Wei S H, Zhang S B, Limpijumnong S 2006 Phys. Rev. B 73 125205
[22] Wang M, Feng M, Zuo X 2014 Appl. Surf. Sci. 292 475
[23] Peng H 2008 Phys. Lett. A 372 1527
[24] Mattioli G, Alippi P, Filippone F, Caminiti R, Amore Bonapasta A 2010 J. Phys. Chem. C 114 21694
[25] Diebold U 2003 Surf. Sci. Rep. 48 53
[26] de Graef M, Mchenry M E 2007 Structure of Materials:An Introduction to Crystallography, Diffraction and Symmetry (Cambridge:Cambridge University Press) p363
[27] Santara B, Giri P K, Imakite K, Fujii M 2014 J. Phys. D:Appl. Phys. 47 215302
[28] Morgan B J, Watson G W 2010 J. Phys. Chem. C 114 2321
[29] Fakhim Lamrani A, Belaiche M, Benyoussef A, El Kenz A, Saidi E H 2010 J. Magn. Magn. Mater. 322 454
[30] Lee H Y, Clark S J, Robertson J 2012 Phys. Rev. B 86 075209
[31] Nolan M, Elliott S D, Mulley J S, Bennett R A, Basham M, Mulheran P 2008 Phys. Rev. B 77 235424
[32] Henderson M A, Epling W S, Peden C H F, Perkins C L 2003 J. Phys. Chem. B 107 534
[33] Yang S, Halliburton L E, Manivannan A, Bunton P H, Baker D B, Klemm M, Horn S, Fujishima A 2009 Appl. Phys. Lett. 94 162114
[34] Santara B, Giri P K, Imakita K, Fujii M 2013 Nanoscale 5 5476
[35] Yosida K 1998 Theory of Magnetism (Berlin:Springer-Verlag) pp87-89
[36] Zhao L, Park S G, Magyari Köpe B, Nishi Y 2013 Math. Comput. Model. 58 275
[37] Zhang Y, Qi Y Y, Hu Y H, Liang P 2013 Chin. Phys. B 22 127101
[38] Rumaiz A K, Ali B, Ceylan A, Boggs M, Beebe T, Shah S I 2007 Solid State Commun. 144 334
[39] Coey J M D, Stamenov P, Gunning R D, Venkatesan M, Paul K 2010 New J. Phys. 12 053025
[40] Finazzi E, Di Valentin C, Pacchioni G 2009 J. Phys. Chem. C 113 3382
[41] Lany S, Zunger A 2009 Phys. Rev. B 80 085202
[42] Kamisaka H, Yamashita K 2011 J. Phys. Chem. C 115 8265
[43] Mulheran P A, Nolan M, Browne C S, Basham M, Sanville E, Bennett R A 2010 Phys. Chem. Chem. Phys. 12 9763
[44] Koudriachova M 2007 Phys. Status Solidi C 4 1205
[45] Zhou S, Čžmár E, Potzger K, Krause M, Talut G, Helm M, Fassbender J, Zvyagin S A, Wosnitza J, Schmidt H 2009 Phys. Rev. B 79 113201
[46] Lai L L, Wu J M 2015 Ceram. Int. 41 12317
[47] Buchholz D B, Chang R P H, Song J Y, Ketterson J B 2005 Appl. Phys. Lett. 87 082504
[48] Ye L H, Freeman A J, Delley B 2006 Phys. Rev. B 73 033203
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[1] Dietl T, Ohno H, Matsukura F, Cibert J, Ferrand D 2000 Science 287 1019
[2] Matsumoto Y, Murakami M, Shono T, Fukumura T, Kawasaki M, Ahmet P, Chikyow T, Koshihara S, Koinuma H 2001 Science 291 854
[3] Higgins J S, Shinde S R, Ogale S B, Venkatesan T, Greene R L 2004 Phys. Rev. B 69 073201
[4] Toyosaki H, Fukumura T, Yamada Y, Nakajima K, Chikyow T, Hasegawa T, Koinuma H, Kawasaki M 2004 Nat. Mater. 3 221
[5] Chambers S A, Wang C M, Thevuthasan S, Droubay T, Mccready D E, Lea A S, Shutthanandan V, Windisch C F 2002 Thin Solid Films 418 197
[6] Hong N H 2006 J. Magn. Magn. Mater. 303 338
[7] Paul S, Choudhury B, Choudhury A 2014 J. Alloy. Compd. 601 201
[8] Kim D H, Yang J S, Kim Y S, Kim D W, Noh T W, Bu S D, Kim Y W, Park Y D, Pearton S J, Jo Y, Park J G 2003 Appl. Phys. Lett. 83 4574
[9] Kang S H, Quynh H N T, Yoon S G, Kim E T, Lee Z, Radmilovic V 2007 Appl. Phys. Lett. 90 102504
[10] Shutthanandan V, Thevuthasan S, Heald S M, Droubay T, Engelhard M H, Kaspar T C, Mccready D E, Saraf L, Chambers S A, Mun B S, Hamdan N, Nachimuthu P, Taylor B, Sears R P, Sinkovic B 2004 Appl. Phys. Lett. 84 4466
[11] Griffin K A, Pakhomov A B, Wang C M, Heald S M, Krishnan K M 2005 Phys. Rev. Lett. 94 157204
[12] Santara B, Pal B, Giri P K 2011 J. Appl. Phys. 110 114322
[13] Pereira L C J, Nunes M R, Monteiro O C, Silvestre A J 2008 Appl. Phys. Lett. 93 222502
[14] Stausholm-Møller J, Kristoffersen H H, Hinnemann B, Madsen G K H, Hammer B 2010 J. Chem. Phys. 133 144708
[15] Shi L B, Wang Y P 2016 J. Magn. Magn. Mater. 405 1
[16] Zarhri Z, Houmad M, Ziat Y, El Rhazouani O, Slassi A, Benyoussef A, El Kenz A 2016 J. Magn. Magn. Mater. 406 212
[17] Kim D, Hong J, Park Y R, Kim K J 2009 J. Phys.:Condens. Matter 21 195405
[18] Máca F, Kudrnovsky J, Drchal V, Bouzerar G 2008 Appl. Phys. Lett. 92 212503
[19] Yang K, Dai Y, Huang B, Feng Y P 2010 Phys. Rev. B 81 033202
[20] Iddir H, Ğt S, Zapol P, Browning N D 2007 Phys. Rev. B 75 073203
[21] Na Phattalung S, Smith M F, Kim K, Du M H, Wei S H, Zhang S B, Limpijumnong S 2006 Phys. Rev. B 73 125205
[22] Wang M, Feng M, Zuo X 2014 Appl. Surf. Sci. 292 475
[23] Peng H 2008 Phys. Lett. A 372 1527
[24] Mattioli G, Alippi P, Filippone F, Caminiti R, Amore Bonapasta A 2010 J. Phys. Chem. C 114 21694
[25] Diebold U 2003 Surf. Sci. Rep. 48 53
[26] de Graef M, Mchenry M E 2007 Structure of Materials:An Introduction to Crystallography, Diffraction and Symmetry (Cambridge:Cambridge University Press) p363
[27] Santara B, Giri P K, Imakite K, Fujii M 2014 J. Phys. D:Appl. Phys. 47 215302
[28] Morgan B J, Watson G W 2010 J. Phys. Chem. C 114 2321
[29] Fakhim Lamrani A, Belaiche M, Benyoussef A, El Kenz A, Saidi E H 2010 J. Magn. Magn. Mater. 322 454
[30] Lee H Y, Clark S J, Robertson J 2012 Phys. Rev. B 86 075209
[31] Nolan M, Elliott S D, Mulley J S, Bennett R A, Basham M, Mulheran P 2008 Phys. Rev. B 77 235424
[32] Henderson M A, Epling W S, Peden C H F, Perkins C L 2003 J. Phys. Chem. B 107 534
[33] Yang S, Halliburton L E, Manivannan A, Bunton P H, Baker D B, Klemm M, Horn S, Fujishima A 2009 Appl. Phys. Lett. 94 162114
[34] Santara B, Giri P K, Imakita K, Fujii M 2013 Nanoscale 5 5476
[35] Yosida K 1998 Theory of Magnetism (Berlin:Springer-Verlag) pp87-89
[36] Zhao L, Park S G, Magyari Köpe B, Nishi Y 2013 Math. Comput. Model. 58 275
[37] Zhang Y, Qi Y Y, Hu Y H, Liang P 2013 Chin. Phys. B 22 127101
[38] Rumaiz A K, Ali B, Ceylan A, Boggs M, Beebe T, Shah S I 2007 Solid State Commun. 144 334
[39] Coey J M D, Stamenov P, Gunning R D, Venkatesan M, Paul K 2010 New J. Phys. 12 053025
[40] Finazzi E, Di Valentin C, Pacchioni G 2009 J. Phys. Chem. C 113 3382
[41] Lany S, Zunger A 2009 Phys. Rev. B 80 085202
[42] Kamisaka H, Yamashita K 2011 J. Phys. Chem. C 115 8265
[43] Mulheran P A, Nolan M, Browne C S, Basham M, Sanville E, Bennett R A 2010 Phys. Chem. Chem. Phys. 12 9763
[44] Koudriachova M 2007 Phys. Status Solidi C 4 1205
[45] Zhou S, Čžmár E, Potzger K, Krause M, Talut G, Helm M, Fassbender J, Zvyagin S A, Wosnitza J, Schmidt H 2009 Phys. Rev. B 79 113201
[46] Lai L L, Wu J M 2015 Ceram. Int. 41 12317
[47] Buchholz D B, Chang R P H, Song J Y, Ketterson J B 2005 Appl. Phys. Lett. 87 082504
[48] Ye L H, Freeman A J, Delley B 2006 Phys. Rev. B 73 033203
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