Magnetoelectric domains and their switching mechanism in a Y -type hexaferrite

Abstract

By employing resonant X-ray microdiffraction, we image the magnetisation and magnetic polarity domains of the Y-type hexaferrite Ba 0.5 Sr 1.5 Mg 2 Fe 12 O 22 . We show that the magnetic polarity domain structure can be controlled by both magnetic and electric fields, and that full inversion of these domains can be achieved simply by reversal of an applied magnetic field in the absence of an electric field bias. Furthermore, we demonstrate that the diffraction intensity measured in different X-ray polarisation channels cannot be reproduced by the accepted model for the polar magnetic structure, known as the 2-fan transverse conical (TC) model. We propose a modification to this model, which achieves good quantitative agreement with all of our data. We show that the deviations from the TC model are large, and may be the result of an internal magnetic chirality, most likely inherited from the parent helical (non-polar) phase. arXiv:1904.01278v2 [cond-mat.mtrl-sci]

Strain-induced robust magnetic anisotropy and room temperature magnetoelectric coupling effect in epitaxial SmFeO3 film

“…However, traditional theory holds that the two orders have incompatible occupation rules and thus lead to extremely rare multiferroic materials in nature [7]. Recently, spin-induced improper ferroelectricity has been widely explored in some oxide materials [8][9][10][11]. In such systems, the ferroelectric and magnetic orders bind each other and may exhibit strong magnetoelectric (ME) coupling effect.…”

Multiple magnetic order parameters coexisting in multiferroic hexaferrites resolved by soft x rays

“…32 This effect is similar to what was observed on a Bragg reflection from a ferromagnet (or ferromagnetic component). 11,13,33 Indeed, such a charge scattering was detected at the family of the commensurate reflections with k = (0,0,1.5), 003n ± 1.5 (n: an integer), in Ba 1.3 Sr 0.7 CoZnFe 11 AlO 22 by an electron diffraction measurement. 16 With the presence of the interference effect, the circular dichroic part in the diffraction intensity of the commensurate reflection is given by…”

“…5 Such techniques have revealed non-trivial responses and couplings among coexisting order parameters in multiferroics. Examples are (i) shared domain walls between two distinct order parameters, 6,7 (ii) formation of charged domain walls associated with a magnetic phase transition despite their energy cost, 8,9 (iii) control of a domain pattern through a cross coupling effect, 10,11 and (iv) an intact domain pattern at flipping an order parameter despite random nucleation/movements of domain walls through full volume of the material. 12,13 These findings indicate that couplings among coexisting order parameters lead to unique phenomena in this class of materials.…”

Broadband transverse susceptibility in multiferroic Y-type hexaferrite Ba0.5Sr1.5Zn2Fe12O22

“…Metal cations occupy four octahedral (18h VI , 6c VI , 3a VI and 3b VI ) and two tetrahedral sites (6c IV and 6c IV *) [20]. In the last years several compounds belonging to this structural phase have been identified as good candidates regarding their magnetoelectric properties, namely Ba 2 Mg 2 Fe 12 O 22 [8][9][10], Ba 0.5 Sr 1.5 Co 2 Fe 12 O 22 (BSFCO) [11,12], Ba 0.5 Sr 1.5 Zn 2 Fe 12 O 22 (BSZFO) [13,14] and Al substituted variants Ba 0.5 Sr 1.5 Co 2 (FeAl) 12 O 22 (BSCFAO) [15][16][17] and Ba 0.5 Sr 1.5 Zn 2 (FeAl) 12 O 22 . (BSZFAO) [18,19].…”

“…As a consequence of this, the compound can exhibit different spiral magnetic structures: proper screw, longitudinal conical (LC), transverse conical (TC), intermediates or collinear [1,8], some of which allow the existence of an induced electric polarization that can be explained according to the inverse Dzyaloshinskii-Moriya effect or spin current model [1]. Recent works also point to the existence of spin chirality and chiral domains in these compounds [17,21,22] Transverse susceptibility (TS) is obtained when the magnetic response of a material is measured in the direction of a small AC applied field perpendicular to a bias DC magnetic field. Is a versatile tool to study singular properties of magnetic systems, especially to obtain their anisotropy and switching field [23,24], and is also a probe of phase transitions caused by anisotropy [25].…”