Magnetic and magnetoelectric properties of substituted M-type SrSc x Fe12 – x O19 hexaferrites

Conical magnetic structures in multiferroic SrScxFe12−xO19 hexaferrites derived from powder neutron diffraction

“…However, the scenario in the hexaferrite compound is by far more complicated, and the fact that the transition temperature T * increases with increasing Sc doping (in agreement with the phase diagrams reported in Ref. [13]) speaks in favor of a higher degree of frustration. It has indeed been observed in SrCr 8 Ga 4 O 19 that nonmagnetic defects can disconnect the magnetic sublattices and even completely prevent long-range order [19].…”

“…Moreover, we find a good consistency with the magnetization maximum shown in Ref. [13]. The propagation vector seems to stay constant at an incommensurate value at low temperature for all investigated samples (Note that the low-temperature lattice constant obtained at T = 2 K on the high-flux diffractometer D1B was used to calculate the incommensurability q l after having indexed the magnetic satellites.…”

“…The approach of explaining the electric polarization by the inverse Dzyaloshinskii-Moriya effect is purely qualitative and does not account for the internal magnetic structure of the blocks composed of different sublattices. To explain the fact that the field dependence of polarization for Y -type hexaferrites is odd, while for Z-type it is even and for M-type it may be of both kinds, one has to make additional assumptions concerning the different types of domain boundaries [10,12,13]. It is shown in our work that conical magnetic structures in M-type Sr-Sc hexaferrites do exist for certain Sc concentrations.…”

“…1) thus determining a specific variation of exchange interactions and magnetic anisotropy resulting in a decrease of spontaneous magnetization and a change in the magnetic structure. Recently, the magnetic and magnetoelectric properties of BaSc x Fe 12−x O 19 and SrSc x Fe 12−x O 19 (x = 1.3-1.7) hexaferrites have been studied [12,13], which has revealed the phase transitions from the high-temperature ferrimagnetic phase to the conical magnetic structure. Furthermore, even the Sr compounds possess a remarkable electric polarization that has not been reported before.…”

“…Therefore, we have deemed it more reasonable to identify the concentration x according to the transition temperatures from the ferrimag- netic to the conical phase given in Ref. [13], where the chemical compositions were verified by x-ray energy-dispersion analysis. Two of our three samples reveal that transition T * at very similar temperatures (see Sec.…”