苝四甲酸二酐有機自旋閥電阻轉換及磁性表現之研究

Abstract

在這份研究中，我們主要觀察了以苝四甲酸二酐為中間層的有機自旋閥的電性和磁性表現。此結構中，介於苝四甲酸二酐有機層和上電極之間有一層部分氧化的氧化鋁，讓整個有機自旋閥呈現非對稱的結構。在電流─電壓的掃描量測中，可以觀察到曲線分裂成相異的兩路徑，此現象展現了此層狀結構具有二重電阻穩態。脈衝式電流的量測結果也顯示此元件也具應用為可變電阻式記憶體的潛力。藉由擬和電流─電壓曲線，推論電荷在此元件層狀結構間的傳導可能是具電荷擷取式的傳遞。此外，我們也對此元件進行穿隧磁阻和磁光克爾效應的量測。此非對稱的層狀結構元件結合了磁性和電阻式記憶體效應，具有可發展成為多功能記憶體的潛力。

In this study, we fabricate organic spin valves (OSVs) in sandwiched structure (//NiFe/CoFe/organic/AlOx/CoFe/) with a thin 3,4,9,10-perylene-tetracarboxylic dianhydride (PTCDA) layer as the organic spacer. The presence of the AlOx layer between PTCDA and the top ferromagnetic electrode makes the junction structure asymmetric. The splitting in I-V curve is observed and represents the bistable resistance states of these junctions. We present the resistance switching behavior of these devices by pulse-current measurement, and demonstrate its potential to be a resistance switching random access memory (RRAM) structure. By fitting of I-V curves, the mechanism of charge transport through these OSVs is proposed to be trap-dependent conduction. We also demonstrate its magnetic properties by magnetoresistance (MR) and magneto-optical Kerr effect (MOKE) measurements. These asymmetric OCVs, combining magnetic and resistance switching properties, could be candidates of multifunctional memory devices.