Mitglied der Helmholtz-Gemeinschaft Giorgi Khazaradze Tbilisi, July10, 2014 Study of hexaferrite Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 by EPR technique

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

Mitglied der Helmholtz-Gemeinschaft 3 Schematic crystal structures of hexaferrites. The (110) cross section views of an M-type (Ba,Sr)Fe 12 O 19, W-type (Ba,Sr)Me 2 Fe 16 O 27, X-type (Ba,Sr) 2 Me 2 Fe 28 O 46, Y-type (Ba,Sr) 2 Me 2 Fe 12 O 22, Z-type (Ba,Sr) 3 Me 2 Fe 24 O 41, and U-type (Ba,Sr) 4 Me 2 Fe 36 O 60 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 :93–110] Type of hexaferrites

Mitglied der Helmholtz-Gemeinschaft 4 a)cristal sructure, b-d magnetic structure of Y-type hehaferrite. b)The proper-screw, c) the transverse-conical, d) the conical Kimura et al., Annu. Rev. Condens.Matter Phys :93–110] abcd

Mitglied der Helmholtz-Gemeinschaft 5 Magnetic field dependence of electric polarization at different Temperatures and magnetic phase diagram of High-T MF hexaferrite Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 with magnetic field perpendicular to the c axis T. Kimura et al. Phys Rev. Lett. 94, (2005)

Mitglied der Helmholtz-Gemeinschaft Short description of EPR Zeeman splitting by magnetic field. 9.6 GHz electromagnetic wave is absorbed. Linewidth of EPR is caused by the interaction between the ions.

Mitglied der Helmholtz-Gemeinschaft A. Maisuradze Aet al., Phys. Rev. Lett., 108, (2012). Idea: apply electric field modulation and try to detect magnetic resonance in ME materials Schematic picture of the experiment and the Magnetic/Electric field directions

Mitglied der Helmholtz-Gemeinschaft Electric-field modulated FMR is selectively sensitive to Magnetoelectric coupling in Cu 2 OSeO 3 A. Maisuradze et al., Phys. Rev. Lett., 108, (2012). Temperature dependence of FMR signals of single-crystal Cu 2 OSeO 3 detected using the MFM technique and the EFM technique

Mitglied der Helmholtz-Gemeinschaft 9 Ferromagnetic resonance in Y-type hexaferrite Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 Angular dependence of the resonance field θ C axis H

Mitglied der Helmholtz-Gemeinschaft 10 Ferromagnetic resonance in Y-type hexaferrite Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 with Electric field modulation FMR signal at Electric field The amplitude of FMR signal as function Electric field

Mitglied der Helmholtz-Gemeinschaft 11 Magnetic and Electric Field Modulated FMR (EFMR) in Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 Angular dependence of the Magnetoelectric (ME) coupling

Mitglied der Helmholtz-Gemeinschaft 12 Summary and Conclusions Ferromagnetic resonance (FMR) in Y-type hexaferrite single crystal Ba 0.6 Sr 1.4 Zn 2 Fe 12 O 22 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

Mitglied der Helmholtz-Gemeinschaft 13 Thanks for your Attention!