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232nd MSL Lecture (Mr. Sebastiaan van Dijken, Aalto Univ., Finland) 

Date/Time 2012/10/18 14:00-15:30
Place J2 Building 3F Room J233
OrganizerMaterials and Structures Laboratory
ContactAssociate Proffessor Tomoyasu Taniyama(ext.:5632)

Subject & Detail

232nd MSL Lecture

Lecturer:Mr. Sebastiaan van Dijken (Professor, NanoSpin, Department of Applied Physics, Aalto University School of Science, Finland) 

Subject:Electric-field control of magnetic domain wall motion and local magnetization dynamics in ferromagnetic-ferroelectric heterostructures

Summary: Spintronic devices currently rely on magnetic switching or controlled motion of domain walls by an external magnetic field or spin-polarized current. Achieving the same degree of magnetic controllability using an electric field has potential advantages including enhanced functionality and low power consumption. Here, an approach to electrically control local magnetic properties, including the writing and erasure of regular ferromagnetic domain patterns and the motion of magnetic domain walls, will be discussed [1-3]. The method is based on recurrent strain transfer from ferroelastic 90 stripe domains in ferroelectric media to continuous magnetostrictive films with negligible magnetocrystalline anisotropy. The dominance of the magnetoelastic anisotropy in these ferromagnetic-ferroelectric heterostructures causes full imprinting of the ferroelectric domain pattern into the ferromagnetic counterpart and strong pinning of ferromagnetic domain walls onto narrow ferroelastic boundaries. As a result, the spin rotation, width, and chirality of the magnetic domain walls can be accurately tuned by a change in the direction or strength of the applied magnetic field [4]. Moreover, optical polarization microscopy of both the ferromagnetic and ferroelectric domain structures reveals that domain correlations and strong inter-ferroic domain wall pinning are maintained in an applied electric field. This leads to unprecedented electric-field control over the formation of ferromagnetic domains and the lateral motion of magnetic domain walls, an accomplishment that opens the way to electric-field driven spintronics. The experiments in this work are complemented by micromagnetic simulations to elucidate the physics of interacting ferromagnetic-ferroelectric domain walls.

[1] T.H.E. Lahtinen, J.O. Tuomi, and S. van Dijken, Adv. Mater. 23, 3187 (2011)
[2] T.H.E. Lahtinen, J.O. Tuomi, and S. van Dijken, IEEE Trans. Magn. 47, 3768 (2011)
[3] T.H.E. Lahtinen, K.J.A. Franke, and S. van Dijken, Nature Scientific Reports 2, 258 (2012)
[4] K.J.A. Franke, T.H.E. Lahtinen, and S. van Dijken, Phys. Rev. B 85, 094423 (2012) 

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