In Situ Observation of Reversible Nanomagnetic Switching Induced by Electric Fields

• Published in: Nano letters 2010-04, Vol.10 (4), p.1219-1223
• Main Authors: Brintlinger, Todd, Lim, Sung-Hwan, Baloch, Kamal H, Alexander, Paris, Qi, Yi, Barry, John, Melngailis, John, Salamanca-Riba, Lourdes, Takeuchi, I, Cumings, John
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electromagnetic Fields; Exact sciences and technology; Magnetic properties and materials; Magnetics; Nanoparticles - chemistry; Nanotechnology - instrumentation; Nanotechnology - methods; Physics; Small particles and nanoscale materials; Studies of specific magnetic materials
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl9036406

We report direct observation of controlled and reversible switching of magnetic domains using static (dc) electric fields applied in situ during Lorentz microscopy. The switching is realized through electromechanical coupling in thin film Fe0.7Ga0.3/BaTiO3 bilayer structures mechanically released from the growth substrate. The domain wall motion is observed dynamically, allowing the direct association of local magnetic ordering throughout a range of applied electric fields. During application of ∼7−11 MV/m electric fields to the piezoelectric BaTiO3 film, local magnetic domains rearrange in the ferromagnetic Fe0.7Ga0.3 layer due to the transfer of strain from the BaTiO3 film. A simulation based on micromagnetic modeling shows a magnetostrictive anisotropy of 25 kPa induced in the Fe0.7Ga0.3 due to the strain. This electric-field-dependent uniaxial anisotropy is proposed as a possible mechanism to control the coercive field during operation of an integrated magnetoelectric memory node.