Correlated Visible-Light Absorption and Intrinsic Magnetism of SrTiO3 Due to Oxygen Deficiency: Bulk or Surface Effect?

Title
Correlated Visible-Light Absorption and Intrinsic Magnetism of SrTiO3 Due to Oxygen Deficiency: Bulk or Surface Effect?
Authors
최희채송진동이광렬김승철
Keywords
Density Functional Theory; First-principles calculations; SrTiO3; Oxygen vacancy; surface defects; magnetism
Issue Date
2015-04
Publisher
Inorganic chemistry
Citation
VOL 54, NO 8, 3759-3765
Abstract
The visible-light absorption and luminescence of wide band gap (3.25 eV) strontium titanate (SrTiO3) are wellknown, in many cases, to originate from the existence of natural oxygen deficiency in the material. In this study based on density functional theory (DFT) calculations, we provide, to the best of our knowledge, the first report indicating that oxygen vacancies in the bulk and on the surfaces of SrTiO3 (STO) play different roles in the optical and magnetic properties. We found that the doubly charged state of oxygen vacancy (VO 2+) is dominant in bulk SrTiO3 and does not contribute to the sub-band gap photoexcitation or intrinsic magnetism of STO. Neutral oxygen vacancies (VO 0 ) on (001) surfaces terminated with both TiO2 and SrO layers induce magnetic moments, which are dependent on the charged state of VO. The calculated absorption spectra for the (001) surfaces exhibit mid-infrared absorption (<0.5 eV) and sub-band gap absorption (2.5&#8722;3.1 eV) due to oxygen vacancies. In particular, VO 0 on the TiO2-terminated surface has a relatively low formation energy and magnetic moments, which can explain the recently observed spin-dependent photon absorptions of STO in a magnetic circular dichroism measurement
URI
http://pubs.kist.re.kr/handle/201004/49628
ISSN
00201669
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KIST Publication > Article
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