magnetic polaron effect in photo-induced phase transition of ferromagnets

2015 Fiscal Year Final Research Report

• Project/Area Number: 24540337
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics I
• Research Institution: University of Fukui (2013-2015); The Institute of Physical and Chemical Research (2012)
• Principal Investigator: Makino Takayuki 福井大学, 工学(系)研究科(研究院), 准教授 (70311363)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 励起子 / 強磁性体 / スピン / ファラデー効果 / 磁気工学 / 超高速レーザー / 非線形分光

Outline of Final Research Achievements

The laser-induced ultrafast spin dynamics have been investigated by time-resolved pump-probe and Faraday rotation spectroscopies in ferromagnetic EuO thin films.
We demonstrate that the laser beam can enhance the magnetization on an ultrafast time scale. The decays time for the magnetization enhancement is about 1 nanosecond. In its temperature dependence, there is a maximum slightly below the Curie temperature associated with this dynamical enhancement of magnetization.
It also dominates the demagnetization counterpart at 55 K. It is attributed that this transient collective ordering to the enhancement of the f-d exchange interaction as a result of photoexcitation. We also observed that the circularly polarized light can control the magnetization precession at 10 K. This takes place within the 100-fs duration of a single laser pulse, through combined contribution from two nonthermal photomagnetic effects, i.e., enhancement of the magnetization and an inverse Faraday effect.

Free Research Field

光物性工学