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S e p t e m b e r 2 4 - 2 6 , 2 0 1 8 | B u d a p e s t , H u n g a r y

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Magnetic Materials 2018

Materials Science and Nanotechnology

Volume 2

MAGNETISM AND

MAGNETIC MATERIALS

International Conference on

Masakazu Matsubara, Mater Sci Nanotechnol 2018, Volume 2

DOMAIN DYNAMICS IN MULTIFERROICS

Masakazu Matsubara

Tohoku University, Japan

pin-spiral multiferroics exhibit a strong coupling between the electric and

magnetic subsystems which is of potential interest for technological ap-

plications. Although these systems have been investigated for more than a

decade, the magnetoelectric domain evolution under external fields is still

largely unknown. Using optical second harmonic generation (SHG) microsco-

py we resolve how electric, magnetic, and optical fields affect the multiferro-

ic domains in the archetypal spin-spiral multiferroic TbMnO

. In consecutive

electric switching cycles, varying multi-domain patterns emerge before a sin-

gle-domain state is obtained. This observation reflects that the domain walls

can easily move without being pinned by, e.g., structural defects. In striking

contrast to the electric-field response, multi-domain patterns persist when

the polarization direction is flopped by applied magnetic fields. Here, a uni-

form polarization rotation is observed within all domains, which incorporates

a transformation of neutral into nominally charged domain walls. Landau-Lif-

shitz-Gilbert simulations reveal that this behavior is intrinsic and provide

first evidence for the scalability of macroscopic magnetoelectric properties

onto the level of domains. Furthermore, in a proof-of-principle experiment we

demonstrate that reversible optical switching of multiferroic order parame-

ter is possible by using light pulses of two different colors, which leads to

sequential laser-controlled writing and erasure of multiferroic (antiferromag-

netic spin-spiral) domains. Opto-magnetism is thus complemented by an im-

portant degree of freedom, namely local control of antiferromagnetism by

means of light.

Fig.1: Electric-field control of multiferroic domains in TbMnO

. (a) Progres-

sion of multiferroic domain structure in a cycled electric field Ec along the c

axis. Bright and dark regions correspond to +Pc and –Pc domains, respective-

ly. (b) Ferroelectric hysteresis loop derived from the areal ratio of +Pc to –Pc

domains in SHG images.

Masakazu Matsubara has completed his PhD from

University of Tokyo, Japan. He is the Associate Pro-

fessor of Tohoku University, Japan.

m-matsubara@m.tohoku.ac.jp

BIOGRAPHY