Orthorhombic Ti2O3: A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide

Handle URI:
http://hdl.handle.net/10754/626637
Title:
Orthorhombic Ti2O3: A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide
Authors:
Li, Yangyang ( 0000-0003-4469-0659 ) ; Weng, Yakui; Yin, Xinmao; Yu, Xiaojiang; Sarath Kumar, S. R.; Wehbe, Nimer; Wu, Haijun; Alshareef, Husam N. ( 0000-0001-5029-2142 ) ; Pennycook, Stephen J.; Breese, Mark B. H.; Chen, Jingsheng; Dong, Shuai; Wu, Tao ( 0000-0003-0845-4827 )
Abstract:
Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long-wavelength regimes. In this work, the discovery of orthorhombic-structured Ti2O3 films is reported as a unique narrow-bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well-known corundum-structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n-type with a very high electron concentration, while the bulk-type trigonal-structured Ti2O3 is p-type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X-ray magnetic circular dichroism measurements. Using first-principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room-temperature ferromagnetism observed in orthorhombic-structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.
KAUST Department:
Materials Science and Engineering Program; Imaging and Characterization Core Lab
Citation:
Li Y, Weng Y, Yin X, Yu X, Kumar SRS, et al. (2017) Orthorhombic Ti2 O3 : A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide. Advanced Functional Materials: 1705657. Available: http://dx.doi.org/10.1002/adfm.201705657.
Publisher:
Wiley-Blackwell
Journal:
Advanced Functional Materials
Issue Date:
16-Dec-2017
DOI:
10.1002/adfm.201705657
Type:
Article
ISSN:
1616-301X
Sponsors:
This work was supported by the King Abdullah University of Science and Technology (KAUST). Y.K.W. and S.D. were supported by National Natural Science Foundation of China (Grant No. 11674055). J.S.C. was supported by the Singapore National Research Foundation under CRP Award No. NRF-CRP10-2012-02 and IIP award No. NRF-IIP001-001.
Additional Links:
http://onlinelibrary.wiley.com/doi/10.1002/adfm.201705657/full
Appears in Collections:
Articles; Advanced Nanofabrication, Imaging and Characterization Core Lab; Materials Science and Engineering Program

Full metadata record

DC FieldValue Language
dc.contributor.authorLi, Yangyangen
dc.contributor.authorWeng, Yakuien
dc.contributor.authorYin, Xinmaoen
dc.contributor.authorYu, Xiaojiangen
dc.contributor.authorSarath Kumar, S. R.en
dc.contributor.authorWehbe, Nimeren
dc.contributor.authorWu, Haijunen
dc.contributor.authorAlshareef, Husam N.en
dc.contributor.authorPennycook, Stephen J.en
dc.contributor.authorBreese, Mark B. H.en
dc.contributor.authorChen, Jingshengen
dc.contributor.authorDong, Shuaien
dc.contributor.authorWu, Taoen
dc.date.accessioned2018-01-01T12:19:04Z-
dc.date.available2018-01-01T12:19:04Z-
dc.date.issued2017-12-16en
dc.identifier.citationLi Y, Weng Y, Yin X, Yu X, Kumar SRS, et al. (2017) Orthorhombic Ti2 O3 : A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxide. Advanced Functional Materials: 1705657. Available: http://dx.doi.org/10.1002/adfm.201705657.en
dc.identifier.issn1616-301Xen
dc.identifier.doi10.1002/adfm.201705657en
dc.identifier.urihttp://hdl.handle.net/10754/626637-
dc.description.abstractMagnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long-wavelength regimes. In this work, the discovery of orthorhombic-structured Ti2O3 films is reported as a unique narrow-bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well-known corundum-structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n-type with a very high electron concentration, while the bulk-type trigonal-structured Ti2O3 is p-type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X-ray magnetic circular dichroism measurements. Using first-principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room-temperature ferromagnetism observed in orthorhombic-structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.en
dc.description.sponsorshipThis work was supported by the King Abdullah University of Science and Technology (KAUST). Y.K.W. and S.D. were supported by National Natural Science Foundation of China (Grant No. 11674055). J.S.C. was supported by the Singapore National Research Foundation under CRP Award No. NRF-CRP10-2012-02 and IIP award No. NRF-IIP001-001.en
dc.publisherWiley-Blackwellen
dc.relation.urlhttp://onlinelibrary.wiley.com/doi/10.1002/adfm.201705657/fullen
dc.subjectFerromagnetic oxidesen
dc.subjectFirst-principles calculationsen
dc.subjectNarrow bandgapsen
dc.subjectOrthorhombicen
dc.subjectTi2O3en
dc.titleOrthorhombic Ti2O3: A Polymorph-Dependent Narrow-Bandgap Ferromagnetic Oxideen
dc.typeArticleen
dc.contributor.departmentMaterials Science and Engineering Programen
dc.contributor.departmentImaging and Characterization Core Laben
dc.identifier.journalAdvanced Functional Materialsen
dc.contributor.institutionDepartment of Materials Science and Engineering; National University of Singapore; Singapore 117575 Singaporeen
dc.contributor.institutionSchool of Physics; Southeast University; Nanjing 211189 Chinaen
dc.contributor.institutionSingapore Synchrotron Light Source; National University of Singapore; 5 Research Link Singapore 117603 Singaporeen
kaust.authorLi, Yangyangen
kaust.authorSarath Kumar, S. R.en
kaust.authorWehbe, Nimeren
kaust.authorAlshareef, Husam N.en
kaust.authorWu, Taoen
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