以磁控濺鍍製備鐵銠薄膜之研究

Study of FeRh Thin Film by Sputtering Method

蔡坤昇(Kun Sheng Tsai)

指導教授 ： 李志浩

國立清華大學/原子科學院/工程與系統科學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00157

摘要

為了研究不同磁性之鐵銠薄膜，以及調控反鐵磁性轉鐵磁性之相變特性，本研究利用磁控共濺鍍方式製備不同成分之鐵銠薄膜，並且利用X光繞射、能量散射X光光譜、超導量子干涉儀等技術研究其晶體結構、成分比例以及磁性等物理及化學特性。
CsCl序化結構的FeRh合金在室溫以上有反鐵磁性轉鐵磁性之相變特性，伴隨著巨大的磁卡效應以及電阻率的改變等卓越的特性，而FeRh的反鐵磁轉鐵磁的相變屬於一次相變，可以運用的範圍只在於發生相轉變的溫度區間，這將會限制FeRh在運用上的發展。為了拓展FeRh的相變區間寬度以及相轉變溫度，並且維持其材料的優越特性，許多研究團隊藉由調控成分比、摻雜、施加介面的應力以及不同的奈米結構等方式來調變相變區間寬度以及相轉變溫度，其中以成分比例的調控影響最劇烈，成分比例些微的差異使得FeRh有著截然不同的磁性。
本研究以共濺鍍方式，並經過後退火處理製備FeRh薄膜。藉由鐵片與銠靶材佔據在濺鍍區域的相對面積多寡，來調控鐵銠薄膜的成分比例，具有可大範圍且趨近線性地調控成分比之特色。
本研究成功利用共濺鍍方式並經過後退火處理製備磊晶結構之鐵銠薄膜，磊晶鐵銠薄膜（100）晶面與MgO基板（100）晶面夾45°，同時也觀察到Fe270°Rh90°系列之鐵銠薄膜隨著不同熱處理溫度而有不同大小的薄膜應變之現象，最後也成功觀察到反鐵磁轉鐵磁之相變隨成分比例的調控而變化。

關鍵字

磁制冷卻 ； 鐵銠合金薄膜 ； 共濺鍍 ； 磊晶結構 ； 相變

並列摘要

To tune the temperature region and temperature change of phase transition from anti-ferromagnetism to ferromagnetism in FeRh thin film, the FeRh thin film were prepared by using magnetron co-sputtering method with different composition. The crystal structure, composition, magnetic properties were measured by X-ray diffraction（XRD）, energy dispersive spectrometer（EDS）, and superconducting quantum interference device（SQUID） respectively.
With phase transition above room temperature, large magnetocaloric effect and giant magnetoresistance, the CsCl FeRh has been focused because of these potential applications, such as refrigeration in room temperature, heat assisted magnetic recording medium and spin valve based devices and so on. However, FeRh belong to first order phase transition material which can be used only at the critical range of phase transition. Therefore, to expand the range of phase transition in FeRh thin film, lots of studies improved it by composition adjustment, doped, interface stress method. Especially, the temperature region and temperature change of phase transition were most sensitive to the composition.
In this work, we focused on composition controlled, the FeRh thin films were prepared with different composition by co-sputtering method via tuning the occupied area between the iron foil and rhodium target on sputtering region.
The results show that the FeRh thin film were epitaxial structure, and the FeRh thin film had a stress which might come from the substrate, and the composition dependence of the phase transition from anti-ferromagnetism to ferromagnetism were observed.

並列關鍵字

Magnetic refrigeration ； FeRh thin film ； Co-sputtering ； Epitaxial structure ； Phase transition

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