Ascienzo David, Yuan Haochen, Greenbaum Steve, Bayer Thorsten J M, Maier Russell A, Wang Jian-Jun, Randall Clive A, Dickey Elizabeth C, Zhao Haibin, Ren Yuhang
Physics & Astronomy, Hunter College, the City University of New York, 695 Park Avenue, New York, NY 10065, USA.
The Graduate Center, the City University of New York, 365 5th Ave., New York, NY 10016, USA.
Materials (Basel). 2016 Oct 31;9(11):883. doi: 10.3390/ma9110883.
We report on the detection of electric field-induced second harmonic generation (EFISHG) from the anode interfaces of reduced and oxidized Fe-doped SrTiO₃ (Fe:STO) single crystals. For the reduced crystal, we observe steady enhancements of the susceptibility components as the imposed -voltage increases. The enhancements are attributed to a field-stabilized electrostriction, leading to Fe:Ti-O bond stretching and bending in Fe:Ti-O₆ octahedra. For the oxidized crystal, no obvious structural changes are observed below 16 kV/cm. Above 16 kV/cm, a sharp enhancement of the susceptibilities occurs due to local electrostrictive deformations in response to oxygen vacancy migrations away from the anode. Differences between the reduced and oxidized crystals are explained by their relative oxygen vacancy and free carrier concentrations which alter internal electric fields present at the Pt/Fe:STO interfaces. Our results show that the optical SHG technique is a powerful tool for detecting structural changes near perovskite-based oxide interfaces due to field-driven oxygen vacancy migration.
我们报道了在还原和氧化的铁掺杂钛酸锶（Fe:STO）单晶的阳极界面处检测到电场诱导二次谐波产生（EFISHG）的情况。对于还原晶体，我们观察到随着施加电压的增加，极化率分量持续增强。这种增强归因于场稳定的电致伸缩，导致Fe:Ti - O键在Fe:Ti - O₆八面体中发生拉伸和弯曲。对于氧化晶体，在16 kV/cm以下未观察到明显的结构变化。在16 kV/cm以上，由于氧空位从阳极迁移导致的局部电致伸缩变形，极化率急剧增强。还原晶体和氧化晶体之间的差异可以通过它们相对的氧空位和自由载流子浓度来解释，这些浓度会改变Pt/Fe:STO界面处存在的内部电场。我们的结果表明，光学二次谐波产生技术是检测钙钛矿基氧化物界面附近由于场驱动氧空位迁移引起的结构变化的有力工具。
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