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We investigated the effect of Al doping in magnetic properties of the Y-type hexaferrite Ba 0.7 Sr 1.3 Zn 2 (Fe 1−x Al x) 12 O 22 (0 x 0.12), which exhibit field-induced magnetoelectric polarization. We find that Al doping increases the pitch of a spin helix and enhances c-axis magnetization, stabilizing longitudinal conical phases. These conical phases eventually collapse at x 0.10. These results suggest that competitions between easy-axis and easy-plane anisotropy fields play a key role in generating stable magnetoelectric polarization in Y-type hexaferrites.

Using magnetoelectric measurements and neutron diffraction, we investigated multiferroic properties of Co 2 Y hexaferrite Ba 0.3 Sr 1.7 Co 2 Fe 12 O 22 in zero and finite magnetic field (H ⊥ c). Upon zero-field cooling, a longitudinal heliconical magnetic structure was observed below 280 K, which involves incommensurate planar helical ordering. When the magnetic field was applied perpendicular to its c axis, electric polarization was observed and the incommensurate ordering was replaced by a commensurate one as commonly observed in other hexaferrites. Electric polarization remained at its maximum during field reversal at 10 K, which indicates that magnetic anisotropy within the basal planes stabilizes the field-induced electric polarization.

Inspired by the role of cellular structures, which give three-dimensional robustness to graphene structures, a new type of graphene cantilever with mechanical resilience is introduced. Here, NH 4 SCN is incorporated into graphene oxide (GO) gel using it as a coagulant for GO fiber self-assembly, a foaming agent, and a dopant. Subsequent thermal treatment of the GO fiber at 600 °C results in the evolution of gaseous species from NH 4 SCN, yielding internally porous graphene cantilevers (NS-GF cantilevers). The results reveal that NS-GF cantilevers are doped with N and S and thus exhibit higher electrical conductivity (150 S cm −1 ) than that of their nonporous counterparts (38.4 S cm −1 ). Unlike conventional fibers, the NS-GF cantilevers exhibit mechanical resilience by bending under applied mechanical force but reverting to the original position upon release. The tip of the NS-GF cantilevers is coated with magnetic Fe 3 O 4 particles, and fast mechanical movement is achieved by applying the magnetic field. Since the NS-GF cantilevers are highly conductive and elastic, they are employed as bendable, magnetodriven electrical switches that could precisely read on/off signals for >10 000 cycles. Our approach suggests a robust fabrication strategy to prepare highly electroconductive and mechanically elastic foam structures by introducing unique organic foaming agents.

Previously we have published the paper titled "Al doping effect on magnetic phase transitions of magnetoelectric hexaferrite Ba 0.7 Sr 1.3 Zn 2 (Fe 1−x Al x ) 12 O 22 " in Physical Review B. Recently, we found that the equation (A4) presented in the Appendix of the paper contains a typographical error. The original equation in the paper containing the error is as follows:The correct form of the equations must be as follows:The error is limited to the last line corresponding to the C and D parameters. The above error is purely typographical, and does not affect interpretation or conclusion of the paper in any way. 059905-1 1098-0121/2012/86(5)/059905 (1)