以飛秒光譜探測系統研究釔錳氧薄膜之電子、聲子與自旋的超快動力學行為

Abstract

在稀土族錳氧化物材料中，因為其具有磁電效應而使得此類材料相當的有趣，而磁電效應與材料中的電子、聲子與自旋的行為有相當密切地關係。在此類材料中釔錳氧化物因為釔離子不具有4f軌域的電子，所以其磁性完全由錳離子所貢獻，所以釔錳氧化物提供了一個相對乾淨的環境來研究此類材料。而本研究係使用脈衝雷射蒸鍍系統分別在MgO(111)、MgO(100)與NGO(001)基板上成長六方晶系或正交晶系之釔錳氧薄膜，並以X光繞射、X光吸收光譜、磁化率等量測確定樣品的晶格結構、電子結構、與磁性行為，並藉由飛秒雷射激發-探測系統研究釔錳氧薄膜，來分析電子、聲子與自旋間偶合的行為。

In RMnO3 compounds, because of it’s magnetoelectric effect these compounds are much interesting. Magnetoelectric effect have relations with the couplings of electron, phonon and spin. In these compounds, YMnO3 with no 4f spin electrons makes it’s magnetism contributed only by Mn3+ ions, so YMnO3 supplies a relatively clarifying environment to study these compounds. In this thesis, YMnO3 thin films were prepared on MgO(111), MgO(100) and NGO(001) substrates with hexagonal or orthogonal phases. The basic characterizations of these thin films, include the crystal structure, electric structure and magnetic properties were measured by X-ray diffraction, X-ray absorption spectrum and magnetization, respectively. Moreover, the YMnO3 thin films were measured by femtosecond pump-probe system to analysis the couplings of electron, phonon and spin.