Insulating Ferromagnetic LaCoO3-δ Films: A Phase Induced by Ordering of Oxygen Vacancies

被引：162

作者：

Biskup, Neven ^{[1
,2
,3
]}

Salafranca, Juan ^{[1
,2
,3
]}

Mehta, Virat ^{[4
,5
]}

Oxley, Mark P. ^{[6
,7
]}

Suzuki, Yuri ^{[4
,5
,8
,9
]}

Pennycook, Stephen J. ^{[3
,6
]}

Pantelides, Sokrates T. ^{[3
,6
,7
]}

Varela, Maria ^{[1
,2
,3
]}

机构：

[1] Univ Complutense Madrid, Dept Fis Aplicada 3, Madrid 28010, Spain

[2] Univ Complutense Madrid, Inst Pluridisciplinar, Madrid 28010, Spain

[3] Oak Ridge Natl Lab, Div Mat Sci & Technol, Oak Ridge, TN 37831 USA

[4] Univ Calif Berkeley, Dept Mat Sci & Engn, Berkeley, CA 94720 USA

[5] Univ Calif Berkeley, Lawrence Berkeley Natl Lab, Div Mat Sci, Berkeley, CA 94720 USA

[6] Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA

[7] Vanderbilt Univ, Dept Elect Engn & Comp Sci, Nashville, TN 37235 USA

[8] Stanford Univ, Dept Appl Phys, Stanford, CA 94305 USA

[9] Stanford Univ, Geballe Lab Adv Mat, Stanford, CA 94305 USA

来源：

PHYSICAL REVIEW LETTERS | 2014年 / 112卷 / 08期

关键词：

PHYSICS; BROWNMILLERITE; STATES; OXIDE;

D O I：

10.1103/PhysRevLett.112.087202

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

The origin of ferromagnetism in strained epitaxial LaCoO3 films has been a long-standing mystery. Here, we combine atomically resolved Z-contrast imaging, electron-energy-loss spectroscopy, and density-functional calculations to demonstrate that, in epitaxial LaCoO3 films, oxygen-vacancy superstructures release strain, control the film's electronic properties, and produce the observed ferromagnetism via the excess electrons in the Co d states. Although oxygen vacancies typically dope a material n-type, we find that ordered vacancies induce Peierls-like minigaps which, combined with strain relaxation, trigger a nonlinear rupture of the energy bands, resulting in insulating behavior.

引用

页数：5

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