Optical and magnetic properties in epitaxial GdN thin film
Optical and magnetic properties in epitaxial GdN thin film
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外延 GdN 薄膜的光学和磁学特性
DOI：
10.1103/physrevb.83.155202
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
and T. Sakurai
中科院分区：
文献类型：
--
作者：
H. Yoshitomi;S. Kitayama;T. Kita;O. Wada;M. Fujisawa;H. Ohta;and T. Sakurai
研究了超纯条件下反应溅射外延生长的AlN/GDN/AlN双异质结的光学和磁学性质。在95 nm厚的GDN薄膜中，间接和直接光学跃迁分别为0.95 eV和1.18 eV。随着GDN厚度的减小，观察到了相当大的光学带隙尺寸效应。AlN/GDN/AlN双异质结在低温下表现出明显的铁磁性。在∼60K以下，自旋的短程关联开始发展，在∼30K以下，长程有序化符合阿罗特关系。由于铁磁有序化与薄膜尺寸无关，我们认为GdN中的协同关联长度小于30 nm。此外，我们还发现，随着铁磁自旋有序的增加，禁带宽度显著减小。
We studied the optical and magnetic properties in epitaxial AlN/GdN/AlN double heterostructures grown using reactive sputtering under ultrapure conditions. The indirect and direct optical transitions in a 95-nm-thick GdN film were found to be 0.95 and 1.18 eV, respectively. The considerable size effects of the optical band gap were observed with a decrease in the GdN thickness. The AlN/GdN/AlN double heterostructures clearly exhibited ferromagnetic states at low temperature. The short-range correlation of spins began to develop below ∼60 K, and long-range ordering that obeyed the Arrott relation was confirmed below ∼30 K. Because of the film-size independence for the ferromagnetic ordering, the cooperative correlation length in GdN was considered to be shorter than 30 nm. Furthermore, we found that the band gap is dramatically reduced with the ferromagnetic spin ordering.