Xu Ruijuan, Huang Jiawei, Barnard Edward S, Hong Seung Sae, Singh Prastuti, Wong Ed K, Jansen Thies, Harbola Varun, Xiao Jun, Wang Bai Yang, Crossley Sam, Lu Di, Liu Shi, Hwang Harold Y
Department of Applied Physics, Stanford University, Stanford, CA, 94305, USA.
Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, CA, 94025, USA.
Nat Commun. 2020 Jun 19;11(1):3141. doi: 10.1038/s41467-020-16912-3.
Advances in complex oxide heteroepitaxy have highlighted the enormous potential of utilizing strain engineering via lattice mismatch to control ferroelectricity in thin-film heterostructures. This approach, however, lacks the ability to produce large and continuously variable strain states, thus limiting the potential for designing and tuning the desired properties of ferroelectric films. Here, we observe and explore dynamic strain-induced ferroelectricity in SrTiO by laminating freestanding oxide films onto a stretchable polymer substrate. Using a combination of scanning probe microscopy, optical second harmonic generation measurements, and atomistic modeling, we demonstrate robust room-temperature ferroelectricity in SrTiO with 2.0% uniaxial tensile strain, corroborated by the notable features of 180° ferroelectric domains and an extrapolated transition temperature of 400 K. Our work reveals the enormous potential of employing oxide membranes to create and enhance ferroelectricity in environmentally benign lead-free oxides, which hold great promise for applications ranging from non-volatile memories and microwave electronics.
复杂氧化物异质外延技术的进展凸显了利用晶格失配产生的应变工程来控制薄膜异质结构中铁电性的巨大潜力。然而，这种方法缺乏产生大的且连续可变应变状态的能力，从而限制了设计和调控铁电薄膜所需特性的潜力。在此，我们通过将独立的氧化物薄膜层压到可拉伸聚合物衬底上，观察并探索了SrTiO中动态应变诱导的铁电性。结合扫描探针显微镜、光学二次谐波产生测量和原子模拟，我们证明了在2.0%单轴拉伸应变下，SrTiO在室温下具有稳健的铁电性，180°铁电畴的显著特征以及400 K的外推转变温度证实了这一点。我们的工作揭示了采用氧化物薄膜在环境友好的无铅氧化物中产生和增强铁电性的巨大潜力，这对于从非易失性存储器到微波电子学等一系列应用都具有广阔前景。
