講演題目: Unraveling thickness-dependent spin relaxation in colossal magnetoresistance manganite films
講演者: Prof. Yu-Miin Sheu (Department of Electrophysics, National Chiao Tung University)
日時: 平成31年1月9日（水） 15:30-16:30
場所：北海道大学電子科学研究所（北キャンパス総合研究棟5号館）１階 セミナー室1-2
概要
Using ultrafast optical spectroscopy, we reveal sensitive spin relaxation in 10-100 nm thick
La_0.7Ca_0.3MnO₃ films, which are typical thicknesses used in operating devices. The spin-lattice relaxation time displays a strong dependence on thickness below the Curie temperature. Compared with our simulation, it is found that such behavior is due to strong temporal variation of thermal gradient, and the observed faster relaxation is not intrinsic (e.g., due to reduced magnetization [1]), but extrinsic, arising from lattice thermal quenching through the substrate, leading to demagnetization quenching. Furthermore, we provide an analytical way to extract the intrinsic spin relaxation time for highly thermal dissipative films. Our study strongly suggests that careful consideration of transient thermal properties in spin manipulation/demagnetization is mandatory when incorporating absorbing thin magnetic films into heterostructures.[2]

Reference:
1. Y. M. Sheu, S. A. Trugman, L. Yan, J. Qi, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, Phys. Rev. X 4, 021001 (2014).
2. Y. M. Sheu, S. A. Trugman, A. P. Chen, J. Qi, Q. X. Jia, A. J. Taylor, and R. P. Prasankumar, Appl. Phys. Lett. 113, 012402 (2018).

主催：北海道大学 電子科学研究所 学術交流委員会
共催：応用物理学会 北海道支部