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26 September 2013 Electric-field control of magnetism in an insulator at room temperature: the case of multiferroic BiFeO3
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The ability to control magnetism using electric fields in non-conducting materials is of great fundamental and practical interest, potentially leading to novel magnetic memories and spin-based devices that dissipate much less energy. The conventional mechanism for electrical control of magnetism has to do with the sensitivity of magnetic anisotropy on the filling of d-bands in ferromagnetic metals and semiconductors. Such a mechanism can not be operative in insulators, implying that E-field control of magnetic order is a great challenge in these materials. An exception to this rule is the room temperature magnetoelectric material bismuth ferrite (BiFeO3 or BFO): In the past few years there were several demonstrations of the control of its magnetic properties by electrically switching its ferroelectric polarization P. Here I review the microscopic origin of these effects, that are mainly due to the electrical manipulation of the spin-current interaction. Nevertheless, the spin-current interaction is not the only magnetoelectric coupling present in BFO. I wil describe recent experimental and theoretical developments that showed that BFO has a strong magnetic anisotropy that scales linearly with an external E-field. This leads to a giant E-field effect on magnon spectra, that is 105 times larger than what is observed in other materials. The E field converts the antiferromagnetic spiral (cycloidal) ground state into a homogeneous antiferromagnet, with a weak ferromagnetic moment whose orientation can be controlled by the E field direction. Remarkably, this kind of E-field control of magnetism occurs without switching P, hence it is expected to be a low energy dissipation process. Thus it might have applications in spin-based devices made of insulators.
© (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Rogério de Sousa "Electric-field control of magnetism in an insulator at room temperature: the case of multiferroic BiFeO3", Proc. SPIE 8813, Spintronics VI, 88131L (26 September 2013);


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