正交與六角結構鋱錳氧薄膜磁性與吸收光譜的各向異性

Abstract

本研究係使用脈衝雷射蒸鍍系統分別在YSZ(111)及NGO(001)上成長出高純相之六角晶系結構及三軸分開的正交晶系結構的鋱錳氧薄膜。不同結構的鋱錳氧薄膜各自擁有其獨特的物理性質。我們利用X光近邊緣吸收結構來探究o相及h相的鋱錳氧薄膜中錳3d軌域之各向異性，從O K-edge及Mn L-edge吸收光譜顯示其強烈的極性相依。同時，也從磁性的量測中發現h相鋱錳氧薄膜在24 K及44 K有兩個有趣的相轉變溫度，初步推測其分別來自於磁彈性效應及Mn3+自旋的再度轉向所導致。本論文對不同結構的鋱錳氧薄膜之極性相依的電子結構和磁性相轉變皆有詳細的研究。

Pure hexagonal and orthorhombic TbMnO3 have been epitaxially deposited on YSZ(111) and NGO(001) substrates, respectively. Both hexagonal and orthorhombic films show their specific mutiferroic signatures. We observed the anisotropic bonding of the Mn 3d valence states in both hexagonal and orthorhombic TbMnO3 thin films by using x-ray absorption near edge structure(XANES). The polarized O K-edge and Mn L-edge x-ray absorption spectra show a strong polarization dependence. We also find interesting anomalies in the magnetic properties of the h-TbMnO3 films at around 24 K and 44 K, which should be related with the magnetoelastic effect and the Mn3+ spin reorientation. This thesis shows details of the anisotropic electronic structure and magnetic properties of h- and o- TbMnO3 films.