The coupling strain in nanoscale systems can achieve control of the physical properties in functional materials, such as ferromagnets, ferroelectrics, and superconductors. Here, we directly demonstrate the atomic-scale structure of super-tetragonal PbTiO3 nanocomposite epitaxial thin films, including the extraordinary coupling of strain transition and the existence of the oxygen vacancies. Large strain gradients, both longitudinal and transverse (∼3 × 107 m-1), have been observed. The original non-magnetic ferroelectric composites notably evoke ferromagnetic properties, derived from the combination of Ti3+ and oxygen vacancies. The saturation ferromagnetic moment can be controlled by the strain of both the interphase and substrate, optimized to a high value of ∼55 emu/cc in 10-nm thick nanocomposite epitaxial thin films on the LaAlO3 substrate. Strain engineering provides a route to explore multiferroic systems in conventional non-magnetic ferroelectric oxides and to create functional data storage devices from both ferroelectrics and ferromagnetics.

中文翻译：

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通过应变工程控制超四方PbTiO3中的可控铁磁性。

纳米级系统中的耦合应变可以控制功能性材料（例如铁磁体，铁电体和超导体）中的物理特性。在这里，我们直接证明了超四方PbTiO3纳米复合外延薄膜的原子尺度结构，包括应变转变的非常规耦合和氧空位的存在。观察到较大的纵向和横向应变梯度（〜3×107 m-1）。原始的非磁性铁电复合材料具有明显的铁磁特性，该特性源自Ti3 +和氧空位的组合。饱和铁磁矩可以通过相间和衬底的应变来控制，并在LaAlO3衬底上的10 nm厚纳米复合外延薄膜中被优化至约55 emu / cc的高值。