Neutron diffraction studies on the multiferroic conical magnet Ba 2 Mg 2 Fe 12 O 22 </…
2010; American Physical Society; Volume: 81; Issue: 17 Linguagem: Inglês
10.1103/physrevb.81.174418
ISSN1550-235X
AutoresShintaro Ishiwata, Daisuke Okuyama, Kazuhisa Kakurai, Masakazu Nishi, Y. Taguchi, Yoshinori Tokura,
Tópico(s)Magnetic and transport properties of perovskites and related materials
ResumoMagnetic structure of a multiferroic Y-type hexaferrite ${\text{Ba}}_{2}{\text{Mg}}_{2}{\text{Fe}}_{12}{\text{O}}_{22}$ with helical-spin structures propagating along [001] below 195 K has been extensively studied, using polarized and unpolarized neutron diffractions under transverse magnetic fields $B$ $(\ensuremath{\perp}[001])$ up to 4.5 T. At zero magnetic field, a longitudinal-conical spin state was found to emerge below about 50 K, which enables the low-$B$ control of electric polarization $P$. The magnetic phase diagram was investigated as a function of transverse $B$ and coexistence of several phases with different helical-spin periodicity was confirmed at low-$B$ region. Furthermore, by using the polarized neutron diffraction under transverse $B$, we verified that the ferroelectric phase with the largest $P$ value with a commensurate ${\mathbit{k}}_{0}$ vector of (0, 0, 3/2) has a transverse-conical spin structure, in which the spin component perpendicular to $B$ shows every $90\ifmmode^\circ\else\textdegree\fi{}$ rotation with translation along the ${\mathbit{k}}_{0}$ direction. The relation between the transverse-conical spin structure and $P$ as a function of the transverse $B$ was discussed in terms of the inverse Dzyaloshinskii-Moriya model.
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