本研究主要是利用X-光散射來測定單晶樣品La1.67Sr0.33NiO4與La1.6Sr0.4NiO4 (LSN) 的晶相及軸向，並使用電性量測分析的方式觀察在此系統中由電荷條紋(charge stripe)所引起的非線性傳輸行為與晶軸的關係，並討論在摻雜量不同時會有何差異。我們主要以電阻-溫度的關係圖(R-T)和電壓-電流曲線(V-I curves)與電流-電壓曲線(I-V curves)等三種曲線來進行數據分析，並藉由量測典型電荷密度波(CDW)系統K0.3MoO3來做為與LSN比較之依據。 從Sr摻雜量不同的兩塊樣品所量測的R-T圖中，不僅觀察到電荷有序排列(charge ordering)的相變溫度點TCO不同，也從不同方向的量測中發現，沿著L方向測量到的電阻率會高於垂直L方向，並從I-V 與V-I curves的量測中發現LSN單晶具有非線性的傳輸行為與記憶效應之特性。我們也發現，改變量測電流的step (DI)，會影響測量之臨界電流值IC；而改變量測電壓的step (DV)，不僅會影響臨界電壓值VT, 且其曲線會隨著step變小而越sharp。 Using x-ray scattering and conductivity measurements, we studied the correlation between the non-linear transport behavior caused by charge stripes and the crystallographic axes in La1.67Sr0.33NiO4 and La1.6Sr0.4NiO4 (LSN). We measured the I-V, V-I curves and the R-T diagrams of both crystals, and compared with with the data obtained from a conventional CDW (charge density wave) material K0.3MoO3. According to the R-T diagrams of two different compositions, we observed the different transition temperatures (TCO) for charge ordering, and the larger resistivity along L direction than that along the H or K directions. From the I-V and V-I curves, we observed the non-linear transport behavior and the switching effect that can be ascribed to be caused by domains. Finally, we also discovered that threshold values of (VT) and (IT) can be changed by applying the different current and voltage steps.
