Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 thin films

dc.contributor.authorKeeney, Lynette
dc.contributor.authorKulkarni, Santosh
dc.contributor.authorDeepak, Nitin
dc.contributor.authorSchmidt, Michael
dc.contributor.authorPetkov, Nikolay
dc.contributor.authorZhang, Panfeng F.
dc.contributor.authorCavill, Stuart
dc.contributor.authorRoy, Saibal
dc.contributor.authorPemble, Martyn E.
dc.contributor.authorWhatmore, Roger W.
dc.contributor.funderHigher Education Authorityen
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderInternational Centre for Graduate Education in Micro and Nano Engineering (ICGEE)en
dc.description.abstractAurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 (BTF7C3O) thin films on α-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn 3 substituted, Bi 5Ti 3Fe 0.7Mn 0.3O 15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the in-plane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, B r, of 6.37 emu/cm 3 (or 804 memu/g), remanent moment 4.99 × 10 -5 emu. The BTF7C3O films were scrutinized by x-ray diffraction, high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis mapping to assess the prospect of the observed multiferroic properties being intrinsic to the main phase. The results of extensive micro-structural phase analysis demonstrated that the BTF7C3O films comprised of a 3.95 Fe/Co-rich spinel phase, likely CoFe 2 - xTi xO 4, which would account for the observed magnetic moment in the films. Additionally, x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) imaging confirmed that the majority of magnetic response arises from the Fe sites of Fe/Co-rich spinel phase inclusions. While the magnetic contribution from the main phase could not be determined by the XMCD-PEEM images, these data however imply that the Bi 5Ti 3Fe 0.7Co 0.3O 15 thin films are likely not single phase multiferroics at room temperature. The PFM results presented demonstrate that the naturally 2D nanostructured Bi 5Ti 3Fe 0.7Co 0.3O 15 phase is a novel ferroelectric and has potential commercial applications in high temperature piezoelectric and ferroelectric memory technologies. The implications for the conclusive demonstration of ferroelectric and ferromagnetic properties in single-phase materials of this type are discussed.en
dc.description.sponsorshipScience Foundation Ireland (SFI the FORME Strategic Research Cluster Award number 07/SRC/I1172 and Starting Investigator Research Grant (09/SIRG/I1621)); European Commission (European Community Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 226716); Higher Education Authority (HEA Program for Research in Third Level Institutions (2007-2011) via the INSPIRE program); International Centre for Graduate Education in Micro & Nano Engineering, (ICGEE Ph.D. funding for N. D.).en
dc.description.statusPeer revieweden
dc.description.versionPublished Versionen
dc.identifier.citationKeeney, L., Santosh, K., Deepak, N., Schmidt, M., Petkov, N., Zhang, P. F., Cavill, S., Roy, S., Pemble, M. E. and Roger W. Whatmore (2012) ' Room temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 thin films', Journal of Applied Physics, 112(5), 052010.
dc.identifier.journaltitleJournal of Applied Physicsen
dc.publisherAIP Publishingen
dc.rights© 2012 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in L. Keeney et al. J. Appl. Phys. 112, 052010 (2012) and may be found at
dc.subjectFerroelectric thin filmsen
dc.subjectMagnetic filmsen
dc.subjectAtomic force microscopyen
dc.subjectX-ray diffractionen
dc.subjectFerromagnetic materialsen
dc.titleRoom temperature ferroelectric and magnetic investigations and detailed phase analysis of Aurivillius phase Bi 5Ti 3Fe 0.7Co 0.3O 15 thin filmsen
dc.typeArticle (peer-reviewed)en
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