Chun-Chien Chiu, Sheng-Zhu Ho, Jenn-Min Lee, Yu-Cheng Shao, Yang Shen, Yu-Chen Liu, Yao-Wen Chang, Yun-Zhe Zheng, Rong Huang, Chun-Fu Chang, Chang-Yang Kuo, Chun-Gang Duan, Shih-Wen Huang, Jan-Chi Yang, Yi-De Chuang
Strontium titanate (STO), with a wide spectrum of emergent properties such as ferroelectricity and superconductivity, has received significant attention in the community of strongly correlated materials. In the strain-free STO film grown on the SrRuO3 buffer layer, the existing polar nanoregions can facilitate room-temperature ferroelectricity when the STO film thickness approaches 10 nm. Here we show that around this thickness scale, the freestanding STO films without the influence of a substrate show the tetragonal structure at room temperature, contrasting with the cubic structure seen in bulk form...
February 23, 2022: Nano Letters