二維材料作為現今熱門研究之一，其中不僅僅是因為其在應用面上有拓展矽半導體製程的可能性，在研究面上當材料縮小到一定尺度，電子將會被侷限而常常導致磁性或電子結構之間會以特別的形式交互影響，而在相異的材料系統中體現豐富的物理特性。其中Freestanding (FS) 技術這項技術已被廣泛的運用在包括微電機系統(MEMs)1,2、sensors3,4等相關應用之中。在科學研究上不僅為整合不同系統材料提供很大的潛力，對於材料應用的開發上，更可以增加調控的自由度。我們在本實驗研究中發現，利用FS 轉移後超薄的鈦酸鍶(SrTiO3, STO)薄膜，可檢驗出顯著的鐵電特性，經過X光繞射的晶格結構鑑定後發現，樣品轉移過後仍然保持tetragonal結構，以及在X光線性二色性吸收光譜(X-ray Linear Dichroism)中確認了原本位於晶格中心的Ti原子偏離了中心位置，結構的不對稱引發出鐵電特性。這個結果不僅提供了一種製備室溫鐵電鈦酸鍶薄膜的方法，還在鐵電性材料中增添了新的選擇，並且在低維度中仍保有鐵電特性，對於鐵電薄膜的應用上，多了更多的可能性，拓展新穎量子材料發展的新思路。

Free-standing (FS) techniques have been adopted in a wide spectrum of applications, including Microelectromechanical Systems (MEMs) , catalysis, sensors, tissue engineering and so on. In academic studies, this technique provides great degrees of freedom and potential for the integration of different material systems. This offers more possibilities for the development of materials.
In this work, we revealed the significant room-temperature ferroelectricity in freestanding strontium titanate (SrTiO3, STO) ultrathin films. The ferroelectric property was verified via conducting Kelvin probe force microscopy (cKPFM), while the lattice exhibits a structure transition from cubic to tetragonal, carried out by reciprocal space mapping. The spatial symmetry breaking of STO lattice is originated from Sr vacancy and polar nanoregion. It leads to the switchable polarity in ultrathin STO thin films. Our results not only provide a promising option served as a candidate of ferroelectric materials but also pave a new way for the development of material integration engineering.

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