超導/磁阻混合感測元件之製作與特性研究

Fabrication and Characteristics of Superconducting/ Magnetoresistive mixed sensors

顏宗揚(Zong-Yang Yan)

指導教授 ： 王立民

國立臺灣大學/理學院/物理研究所/碩士(2014年)

https://doi.org/10.6342/NTU.2014.10395

摘要

本篇論文研究超導/磁阻混合感測元件，主要結構為釔鋇銅氧(YBCO)/二氧化鈰(CeO2)/鑭鈣錳氧(LCMO)，我們利用脈衝雷射蒸鍍在鈦酸鍶(SrTiO3)基板上沉積鑭鈣錳氧鐵磁性薄膜，經過黃光微影與離子蝕刻後，再以脈衝雷射蒸鍍成長二氧化鈰以及釔鋇銅氧高溫超導薄膜，藉由絕緣層來隔絕上下的超導層與鐵磁層。利用X-光繞射儀與原子力顯微鏡來分析薄膜的特性、四點量測和磁性量測系統對元件進行電性與磁性的探討。
我們設計兩種不同磁阻類型的元件，一是以鑭鈣錳氧薄膜為主，另一是製作階梯式穿隧磁阻元件(TMR)，利用離子蝕刻在基板上蝕刻出階梯。測量製作出來的鑭鈣錳氧相轉變溫度為256 K以及釔鋇銅氧有良好的臨界溫度，並量測元件的特性。我們比較有超導環以及沒有超導環的樣品，發現沒有超導環在230 K的環境下其穿隧磁阻最大值達37 %。

關鍵字

釔鋇銅氧 ； 鑭鈣錳氧 ； 磁阻 ； 階梯式

並列摘要

In the thesis, we have studied the superconducting / magnetoresistive mixed sensors, which structure is YBCO/CeO2/ LCMO. The LCMO layers are grown on STO substrates by using plused layser deposition (PLD). Then we define the pattern by photo lithography and ion-milling. CeO2 and YBCO films are grown by PLD. The CeO2 layer is to avoid short between superconducting and ferromagnetism layer. The crystalline orientation and surface morphology are characterized by X-ray diffraction and atomic force microscope (AFM). The electric and magnetic properties are also studied by using four-point probe and magnetic property measurement system.
We design two different type of magnetoresistance device. One is based on LCMO thin films, the other is tunneling magnetoresistance (TMR) junctions with artificial step-edge grain boundaries by using ion-milling. The metal-insulator transition temperature of LCMO is 256 K and superconducting YBCO films reveal a high transition TC. By measuring the characteristics of the divice, we find the maximum TMRmax is 37 %, which is non-YBCO loops in 230 K.

並列關鍵字

YBCO ； LCMO ； magnetoresistanc ； step-edge

參考文獻

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