高溫超導量子干涉柵之製作與特性分析

Fabrication and Characterization of the High-Tc Superconducting Quantum Interference Grating

黃凱顯(Kai-Hsien Huang)

指導教授 ： 鄭振宗

國立臺北科技大學/機電學院/製造科技研究所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00392

摘要

近數十年以來，材料科學與微奈米工程技術的長足進步，造就了多種靈敏的磁場感測器，例如異性磁阻、巨磁阻、磁通閘、核磁共振、以及超導量子干涉元件 (Superconducting QUantum Interference Device, 簡稱 SQUID) 磁力計等。在這些技術中，SQUID磁力計的磁場靈敏度最高、頻寬最大，目前它已成為極微小磁場 (1 pT以下) 的最重要量測技術，可應用於非破壞檢測、心磁波、腦磁波等。
超導量子干涉柵(Superconducting Quantum Interference Grating, 簡稱 SQIG)係由多個約瑟芬接面透過超導迴路並聯而成，其受磁通調節的臨界電流振幅會隨著接面並聯的數目增加，使磁通-電流轉換函數快速的提高，進而降低其磁通雜訊。我們以高溫超導體YBa2Cu3O7-y製作了由11個約瑟芬接面並聯而成的SQIG，並測量它們的電壓-電流、電壓-磁通以及電流-磁通特性，發現其磁通-電流轉換函數增大了約45倍。此結果顯示，SQIG的磁通雜訊至少可以降低到雙約瑟芬接面SQUID的十分之一左右，它在微小磁場測量應用的潛力值得繼續深入研究。

關鍵字

超導量子干涉元件 ； 超導量子干涉柵 ； 約瑟芬接面 ； 磁通-電流轉移函數 ； 高溫超導體

並列摘要

The advancement of the materials science and the micro-and-nano engineering has led to the invention of many sensitive magnetic sensors, e.g. the anisotropic magnetoresistance (AMR), the giant magnetoresistance (GMR), the fluxgate magnetometer, and the superconducting quantum interference device (SQUID). Among these technologies, the SQUID is the most important for measuring the tiny magnetic field below 1 pT. The potential applications include the nondestructive evaluation (NDE), magnetocardiography (MCG), and Magnetoencephalography (MEG).
In this work, the characteristics of the superconducting quantum interference gratings (SQIG) consisting of many Josephson junctions in parallel are investigated. The flux-modulated critical-current amplitude and the flux-to-current transfer function of SQIG were expected to increase with more Josephson junctions in parallel. This feature leads to the reduction in magnetic flux noise. To verify the prediction experimentally, the voltage-current, voltage-flux, and current-flux characteristics were measured for the two-junction dc SQUID and the 11-junction SQIG made from YBa2Cu3O7-y thin films. It was found that the flux-to-current transfer function of the SQIG increased by 45 times in comparison with the two-junction SQUID on the same chip. The result revealed the possibility to enhance the magnetic-flux sensitivity by one order of magnitude with the SQIG.

並列關鍵字

Superconducting quantum interference device ； Superconducting quantum interference grating ； Josephson junction ； Flux-to-current transfer function ； High-transition-temperature superconductor

參考文獻

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