自組裝單分子層有機自旋閥中電阻轉換及磁傳輸特性之研究

Abstract

在我們的研究中，自組裝單分子層的技術被應用在有機自旋閥中之間隔層，企圖減少幾何結構接觸所影響的問題。自組裝單分子層是一種分子材料可以自發性地與特定的基板材料產生鍵結，且形成一層高品質的單分子層，此性質提供了有機自旋閥一個良好排列的分子位障。我們的元件在室溫下展現0.3%的磁電阻效應，且在20K的溫度下增加到2.5%，有趣的是，此有機自旋閥也展現了憶阻器的特徵，且可以在高電阻態及低電阻態之間做電阻式的切換。藉由輸入脈衝電流的方式，讀取－寫入－讀取－抹去的循環也被呈現。為了瞭解電子在自組裝單分子層間傳輸及造成電阻式切換的機制，我們利用模型，例如賽門斯模型（Simmons' formula），去擬和電流－電壓曲線，得出一個合理的解釋。簡而言之，此有機自旋閥結合了磁性與電性的記憶效應而具有潛力發展成一個多功能非揮發性記憶體。

In this study, self-assembled monolayer (SAM) is applied into organic spin valves (OSVs) as a monolayer spacer to reduce the local contact geometry issue. Self-assembled monolayer is one kind of molecular materials would form spontaneously on certain substrate and is organized into a high quality monolayer, which provides well-ordered molecular barrier in OSVs. The devices show magnetoresistance of 0.3% at room temperature and up to 2.5% at 20K. Interestingly, The organic spin valve also shows the fingerprint of memristor, and a resistive switching between a low resistance state and a high resistance state. And the write- read-erase-read cycles is presented by applying current pulse. To understand how charge transport in self-assembled monolayer and what cause the resistive switching, models, such as Simmons' formula, was applied to fit the I-V curve and to speculate a reasonable explanation. In brief, combining magnetic and electric memory effects in an organic spin valve, the device has potential for application to a multifunctional memory device.