Electrical and mechanical switching of ferroelectric polarization in the 70 nm BiFeO3 film.
Electrical and mechanical switching of ferroelectric polarization in the 70 nm BiFeO3 film.
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70 nm BiFeO3 薄膜中铁电极化的电学和机械转换
DOI：
10.1038/srep19092
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发表时间：
2016-01-11
影响因子：
4.6
通讯作者：
Liu Z
中科院分区：
文献类型：
--
作者：
Chen L;Cheng Z;Xu W;Meng X;Yuan G;Liu J;Liu Z
铁电极化开关及其域演化对铁电或压电器件的宏观电学性能起着至关重要的作用。在~5 nm的BaTiO3和PbZr0.2Ti0.8O3外延薄膜上进行了机械开关的研究；然而，对于机械力来说，要像电场一样切换稍微厚一点的薄膜的极化仍然是一个挑战。在这里，我们报道了一个70 nm的BiFeO3外延膜的极化可以通过机械力完全切换，并且其畴演变与电开关观察到的相似。随着场/力的逐渐增大，新的畴优先在畴边界处成核，μm大小的畴通常分解成大量的nm大小的畴，最后重新组织成μm大小的畴，经过多步180度的极化开关。重要的是，在具有光滑表面的（0 0 1）薄膜中也建立了极化的完全机械开关。此外，向上或向下的极化都可以用恒流无损地读出。我们的研究揭示了铁电体在没有电场的情况下的潜在应用，如存储设备和其他微机电系统。
Ferroelectric polarization switching and its domain evolution play a key role on the macroscopic electric properties of ferroelectric or piezoelectric devices. Mechanical switching has been reported recently in ~5 nm BaTiO3 and PbZr0.2Ti0.8O3 epitaxial films; however it is still a challenge for a mechanical force to switch polarization of a slightly thicker film in the same way as an electric field. Here, we report that the polarization of a 70 nm BiFeO3 epitaxial film can be completely switched by a mechanical force and its domain evolution is similar to that observed with electrical switching. With the gradual increase of the field/force, new domains nucleate preferentially at domain boundaries, the μm-size domains commonly decompose to a mass of nm-size domains and finally they may reorganize to μm-size domains which undergo 180o polarization switching through multi steps. Importantly, the complete mechanical switching of polarization was also established in the (0 0 1) film with a smooth surface. Furthermore, either upward or downward polarization can be read out nondestructively by a constant current. Our study sheds light on prospective applications of ferroelectrics in the absence of an electric field, such as memory devices and other micro-electromechanical systems.