鎳酸鑭LaNiO3(LNO)是稀土鎳酸鹽系RNiO3(R代表溪土元素)材料中較受歡迎的材料，主要原因是它在低溫的時候不具有金屬-絕緣轉變(Metal–insulator transition, MIT)，在低溫時依然保有金屬性質，成為RNiO3家族的一個特例。而近年來，又有研究指出，LNO在特定條件下，可能具有拓樸性質，更提升了它的研究熱度。加上近期的拓樸超導體的相關研究也日益升高，且晶格常數與YBa2Cu3O7-x(YBCO)相近，於是我們利用磁控濺鍍的方式，將兩種材料結合，生成雙層薄膜，並量測磁性與電性，探討是否有新發現。
本研究首先討論LNO薄膜的生長條件，針對基板與生長溫度作探討，發現其在不同基板上生長出來的晶格常數會有所變化，而MgO基板則因為匹配度的問題無法成功生長，而580 ℃到720 ℃之間電阻率與晶格常數雖然有變化，但其影響幾乎可以忽略。
由於前述原因，於是雙層薄膜我們以YBCO的最佳生長條件為依據，生長溫度定為720 ℃，並使用SrTiO3(STO)基板與LaAlO3(LAO)基板作探討。將LNO固定為20 nm，分別生長100 nm與50 nm雙層膜，其中我們發現雙層薄膜的超導臨界溫度皆低於YBCO，分別為79.1 K、65 K(磁性量測部分)，遠低於YBCO的85.8 K左右，而我們推斷原因為LNO晶格結構造成YBCO b軸上的氧缺失，並利用XRD證明其推測。而從磁性量測我們得到了雙層薄膜LNO/YBCO 20/100 nm與20/50 nm 的Hc1分別為4.15 Oe與3.03 Oe，Hc2為3.66 T 與1.85 T，我們還發現Jc會隨著LNO占比下降，其中LNO/YBCO 為20/50 nm的樣品，在H=0的時候，Jc有被抑制的現象產生，推斷可能與LNO反應有關。並從Fp來推斷其可能為二維釘扎形式。
而從電性量測發現，LNO/YBCO 20/100 nm時的Tc明顯比磁性量測還低，降低了約13 K左右，判斷可能與蝕刻的影響有關，而從U- H圖可以看出他們具有二維性質。

Lanthanum Nickelate (LaNiO₃, LNO) is one of the more prominent materials in the rare-earth nickelate series (RNiO₃), primarily because it does not exhibit a metal-insulator transition (MIT) at low temperatures. Unlike other members of the RNiO₃ family, LNO retains its metallic properties even at low temperatures, making it a unique exception within this group. Recent studies have further highlighted LNO's potential topological properties under specific conditions, thereby increasing its research interest. Additionally, with the growing interest in topological superconductors and given that LNO's lattice constant is similar to that of YBCO, we employed magnetron sputtering to combine these two materials, creating a bilayer thin film. We then measured its magnetic and electrical properties to investigate the possibility of new discoveries.
This study first examines the growth conditions of LNO thin films, focusing on the substrate and growth temperature. It was found that the lattice constant of the films varies depending on the substrate used. Specifically, the MgO substrate was unable to support successful growth due to a mismatch issue. While there were observable changes in both resistivity and lattice constant within the temperature range of 580°C to 720°C, the impact of these changes is considered negligible.
Based on the aforementioned considerations, the growth conditions for the bilayer thin films were determined using the optimal growth conditions for YBCO, with the growth temperature set at 720°C. STO and LAO substrates were used for further investigation. The LNO layer was fixed at 20 nm, and bilayer films of 100 nm and 50 nm thicknesses were grown. It was observed that the superconducting critical temperatures of the bilayer films were lower than that of YBCO, specifically 79.1 K and 65 K (from magnetic measurements), which are significantly lower than the typical 85.8 K for YBCO. We hypothesize that this reduction is due to oxygen deficiency along the b-axis of YBCO induced by the LNO lattice structure, a hypothesis supported by XRD analysis.
Magnetic measurements of the bilayer films LNO/YBCO 20/100 nm and 20/50 nm revealed Hc1 values of 4.15 Oe and 3.03 Oe, and Hc2 values of 3.66 T and 1.85 T, respectively. Additionally, we found that the critical current density (Jc) decreases as the proportion of LNO decreases. Specifically, the LNO/YBCO 20/50 nm sample exhibited suppressed Jc at H = 0, which we suspect is related to interactions with LNO. Analysis of the pinning force (Fp) suggests that a two-dimensional pinning mechanism may be at play.
Electrical measurements revealed that the Tc of the LNO/YBCO 20/100 nm bilayer is significantly lower than that observed in magnetic measurements, with a reduction of approximately 13 K. This discrepancy is likely due to the effects of etching. Additionally, the U-H curve indicates that these bilayers exhibit two-dimensional characteristics.

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