正交結構鎦錳氧薄膜之磁各向異性研究

Abstract

本實驗使用脈衝雷射濺鍍系統在LAO(110)基板上成功成長出高純相且軸向明確之正交結構鎦錳氧薄膜，以進一步了解E-phase的稀土錳氧化物獨特的物理性質。我們使用超導量子干涉儀量測磁化率與溫度變化關係時，發現正交結構鎦錳氧化合物之磁結構特性，具有非常顯著的各向異性。量測中發現鎦錳氧薄膜在b軸方向約33 K有明顯的反鐵磁構造相稱-不相稱的相轉變，和理論的預測的磁性結構相近；本論文同時將得到的結果與釔錳氧及鈥錳氧的結果比較，以探討離子半徑的改變導致之晶格扭曲對磁性產生的影響。

Orthorhombic phase of LuMnO3 thin films were epitaxially deposited on LAO(110) substrates by pulse laser deposition (PLD). The obtained films not only exhibit highly b axis oriented characteristic but also nearly perfect a-c plane alignment with the substrate .As a result, the current films have allowed us to analyze the anisotropic magnetic property of orthorhombic LuMnO3 thin film. In addition to the usual anti-ferromagnetic (AFM) transition around 42 K, we find the second transition at 33 K along the b-axis, presumably to be associated with the commensurate- incommensurete transition of AFM ordering. The result is consistent with the theoretical prediction of E-phase structure of ReMnO3. By comparing with the results obtained in YMnO3 and HoMnO3, we found the lattice distortion originated from ionic size variations in playing an important role in magnetic property of these mutiferroic rare-earth manganites. Finally, We will also report on the anisotropic magnetic properties displayed in these o- LuMnO3 thin films.