2017/03/23(Thu) 11:00 -12:00 四樓P4H會議室 4F, P4H Meeting Room
Title
Photocreating supercooled spiral-spin states in a multiferroic manganite
Speaker
許鈺敏 助理教授 (國立交通大學電子物理系) Assistant Professor, Yu-Miin Sheu (Department of Electrophysics, National Chiao Tung University)Abstract
I will demonstrate that dynamics of the ab-spiral-spin order in a magnetoelectric multiferroic Eu0.55Y0.45MnO3 (EYMO) can be unambiguously probed through optical second harmonic signal, generated via the spin-induced ferroelectric polarization. In case of relatively weak photoexcitation, the ferroelectric and spiral-spin orders remain interlocked while relaxing through spin-lattice relaxation in the non-equilibrium state. When the additional optical pulse illuminating sample is intense enough to induced local phase transition thermally, the system creates a metastable state of bc-spiral-spin order (with electric polarization P//c) via supercooling across the first-order phase transition between the ab- and bc-spiral. The supercooled state of bc-spiral spin is formed in thermodynamical ground state of the ab-spiral (P//a), displaying a prolonged lifetime, in particular under its favorable magnetic field along the a-axis. [1] The observed photo-switching between the two distinct multiferroic states sheds light on novel photoinduced phenomena in spiral-spin multiferroics.
CV
Language
演講語言 (Language): in Mandarin