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Giorgi Khazaradze

Study of hexaferrite Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 by EPR technique. Giorgi Khazaradze. Tbilisi, July 10, 2014. What is Multiferroics ?. Ferroelectric and Ferromagnetic orderings. Schematic picture of Multiferroic. Read with GMR. MF-RAM. Cycloidal spin ordering. Multiferroic.

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Giorgi Khazaradze

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  1. Study of hexaferriteBa0.6Sr1.4Zn2Fe12O22by EPR technique Giorgi Khazaradze Tbilisi, July10, 2014

  2. What is Multiferroics? Ferroelectric and Ferromagnetic orderings Schematic picture of Multiferroic Read with GMR MF-RAM Cycloidal spin ordering Multiferroic Write with a voltage Magnetoelectric effect P=α H • M=α E Dzyaloshinskii-Morya interaction D. Khomshii, Physics 2, 20 (2009) [M. Bibes and A. Barthélémy, Nat. Mater. 7, 425 (2008)]

  3. Type of hexaferrites Schematic crystal structures of hexaferrites. The (110) cross section views of an M-type (Ba,Sr)Fe12O19, W-type (Ba,Sr)Me2 Fe16O27, X-type (Ba,Sr)2 Me2Fe28 O46 , Y-type (Ba,Sr)2Me2 Fe12O22, Z-type (Ba,Sr)3Me2 Fe24 O41 , and U-type (Ba,Sr)4Me2Fe36O60 with the c axis vertical. The (Fe,Me)-O-(Fe,Me) bond angles surrounded by dashed blue ellipsoids are strongly affected by the ratio of Sr to Ba. Kimura et al., Annu. Rev. Condens.Matter Phys. 2012. 3:93–110]

  4. a b c d cristalsructure, b-d magnetic structure of Y-type hehaferrite. The proper-screw, c) the transverse-conical, d) the conical Kimura et al., Annu. Rev. Condens.Matter Phys. 2012. 3:93–110]

  5. Magnetic field dependence of electric polarization at different Temperatures and magnetic phase diagram of High-T MF hexaferriteBa0.5Sr1.5Zn2Fe12O22with magnetic field perpendicular to the c axis T. Kimura et al. Phys Rev. Lett. 94,137201 (2005)

  6. Zeeman splitting by magnetic field. 9.6 GHz electromagnetic wave is absorbed. Linewidth of EPR is caused by the interaction between the ions. Short description of EPR

  7. Idea: apply electric field modulation andtry to detect magnetic resonance in ME materials Schematic picture of the experiment and the Magnetic/Electric field directions A. MaisuradzeAetal., Phys. Rev. Lett., 108, 247211 (2012).

  8. Electric-field modulated FMR is selectively sensitive to Magnetoelectric coupling in Cu2OSeO3 Temperature dependence of FMR signals of single-crystal Cu2OSeO3 detected using the MFM technique and the EFM technique A. Maisuradzeet al., Phys. Rev. Lett., 108, 247211 (2012).

  9. Ferromagnetic resonance in Y-type hexaferrite Ba0.6Sr1.4Zn2Fe12O22 Angular dependence of the resonance field H C axis θ

  10. Ferromagnetic resonance in Y-type hexaferrite Ba0.6Sr1.4Zn2Fe12O22 with Electric field modulation The amplitude of FMR signal as function Electric field FMR signal at Electric field

  11. Magnetic and Electric Field Modulated FMR (EFMR) in Ba0.6Sr1.4Zn2Fe12O22 Angular dependence of the Magnetoelectric (ME) coupling

  12. Summary and Conclusions • Ferromagnetic resonance (FMR) inY-type hexaferrite single crystal Ba0.6Sr1.4Zn2Fe12O22 was observed. • Using electric field modulation FMR (EFMR) technique magnetoelectric coupling was observed in this compound. • Magnetoelectric coupling was estimated, however it is week at room temperature. • Magnetoelectric coupling was determined quantitatively as a function of temperature and magnetic field orientation. • The next step would be to study this compound at lower temperatures and appropriate magnetic field range where electric polarization was observed by using Soft X-ray Scattering method. Outlook

  13. Thanks for your Attention!

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