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Title: Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6

Authors:
 [1];  [2];  [2];  [3];  [4];  [2];  [2];  [2];  [5]
  1. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  2. Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  3. Material Science Division, Argonne National Laboratory, Lemond, Illinois 60439, USA
  4. Stanford Synchrotron Radiation Laboratory, Mailstop 69, Menlo Park, California 94025, USA
  5. Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA, Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
Publication Date:
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1420587
Grant/Contract Number:
AC52- 06NA25396; AC02-76SF00515
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 24; Related Information: CHORUS Timestamp: 2018-02-14 14:39:45; Journal ID: ISSN 0003-6951
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Ahmed, Towfiq, Chen, Aiping, McFarland, Brian, Wang, Qiang, Ohldag, Hendrik, Sandberg, Richard, Jia, Quanxi, Yarotski, Dmitry A., and Zhu, Jian-Xin. Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6. United States: N. p., 2016. Web. doi:10.1063/1.4953828.
Ahmed, Towfiq, Chen, Aiping, McFarland, Brian, Wang, Qiang, Ohldag, Hendrik, Sandberg, Richard, Jia, Quanxi, Yarotski, Dmitry A., & Zhu, Jian-Xin. Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6. United States. doi:10.1063/1.4953828.
Ahmed, Towfiq, Chen, Aiping, McFarland, Brian, Wang, Qiang, Ohldag, Hendrik, Sandberg, Richard, Jia, Quanxi, Yarotski, Dmitry A., and Zhu, Jian-Xin. 2016. "Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6". United States. doi:10.1063/1.4953828.
@article{osti_1420587,
title = {Site-mixing effect on the XMCD spectrum in double perovskite Bi 2 FeMnO 6},
author = {Ahmed, Towfiq and Chen, Aiping and McFarland, Brian and Wang, Qiang and Ohldag, Hendrik and Sandberg, Richard and Jia, Quanxi and Yarotski, Dmitry A. and Zhu, Jian-Xin},
abstractNote = {},
doi = {10.1063/1.4953828},
journal = {Applied Physics Letters},
number = 24,
volume = 108,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4953828

Citation Metrics:
Cited by: 5works
Citation information provided by
Web of Science

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  • We investigate magnetization in double perovskite multiferroic Bi2FeMnO6 (BFMO) thin film using density functional theory (DFT) simulations, and X-ray magnetic circular dichroism (XMCD) measurements. The exchange interaction between Fe and Mn sites gives rise to a ferrimagnetic ordering in BFMO. When grown without structural defects, distinct XMCD signal is expected from this system. The site resolved magnetization, thus, can be extracted using XMCD sum rules. Although our theoretical calculations are consistent with this expectation for the ideal BFMO system, experimental measurements find evidence of anomalous peak for the L-2 and L-3 edges of XMCD signals, and thus, the XMCD summore » rules are no longer valid. We theoretically explain this phenomenon by considering both tetragonal (near interface), and monoclinic (bulk) phases of BFMO system, with Fe and Mn ions interchanged between their respective sites. Such site-mixing between magnetic cations are commonly found during the synthesis process. Our DFT calculations of XMCD for site interchanged Fe and Mn ions in the bulk phase (monoclinic) of BFMO are in good agreement with experimental XMCD signal and reproduce the anomalous peak features at L-2/L-3 edges.« less
  • Cited by 5
  • Cited by 5
  • Two types of chemical-pressure effects on the Verwey-type transition in BaSmFe{sub 2}O{sub 5} are studied, viz., ionic-size contractions at the Ba and Sm sites. Whereas the replacement of Sm by the smaller Eu and Gd atoms increases the transition temperature T{sub V} from 232 K to 264 K, the Sr-for-Ba substitution decreases it from 232 K to 180 K for x=0.15 in (Ba{sub 1-x}Sr{sub x})SmFe{sub 2}O{sub 5}. Of various structural parameters determined by synchrotron x-ray diffraction above T{sub V}, the magnitude of the orthorhombic distortion (=b-a) is found to correlate with T{sub V} in a manner that unifies both substitutionmore » schemes. It is suggested that when an increase in b-a above T{sub V} is achieved by means of the structural substitution, it makes it easier for the d{sub xz} Fe{sup 2+} orbital ordering to occur below T{sub V}.« less
  • Ordering of Fe{sup 3+} and Fe{sup 2+} between octahedral (Oh) and tetrahedral (Td) sites in synthetic members of the magnetite (Fe{sub 3}O{sub 4}) - ulvoespinel (Fe{sub 2}TiO{sub 4}) solid-solution series was determined using Fe L{sub 2,3}-edge X-ray magnetic circular dichroism (XMCD) coupled with electron microprobe and chemical analysis, Ti L-edge spectroscopy, Fe K-edge EXAFS and XANES, Fe{sub 57} Moessbauer spectroscopy, and unit cell parameters. Microprobe analysis, cell edges and chemical FeO determinations showed that the bulk compositions of the samples were stoichiometric magnetite-ulvoespinel solid-solutions. Surface sensitive XMCD showed that the surfaces of these oxide minerals were more sensitive to redoxmore » conditions and some samples required re-equilibration with suitable solid-solid buffers. Detailed site-occupancy analysis of these samples gave XMCD-Fe{sup 2+}/Fe{sup 3+} ratios very close to stoichiometric values. L{sub 2,3}-edge spectroscopy showed that Ti{sup 4+} was restricted to Oh sites. XMCD results showed that significant Fe{sup 2+} only entered Td when the Ti content was > 0.40 apfu while Fe{sup 2+} in Oh increased from 1 a.p.f.u in magnetite to a maximum of {approx}1.4 apfu in USP45. As the Ti content increased from this point, the steady increase in Fe{sup 2+} in Td sites was clearly observable in the XMCD spectra, concurrent with a slow decrease in Fe{sup 2+} in Oh sites. Calculated magnetic moments showed a steady decrease from magnetite (4.06 {mu}{sub B}) to USP45 (1.5 {mu}{sub B}) and then a slower decrease towards the value for ulvoespinel (0 {mu}{sub B}). Two of the synthesized samples were also partially maghemitized by re-equilibrating with an oxidizing Ni-NiO buffer and XMCD showed that Fe{sup 2+} oxidation only occurred at Oh sites, with concomitant vacancy formation restricted to this site. This study shows the advantage of using XMCD as a direct measurement of Fe oxidation state in these complex magnetic spinels. These results can be used to rationalize the magnetic properties of titanomagnetites, and their oxidized titanomaghemitized analogues, in Earth's crustal rocks.« less