Enhanced conductivity at specific domain walls in ferroelectrics is now an established phenomenon. Surprisingly, however, little is known about the most fundamental aspects of conduction. Carrier types, densities and mobilities have not been determined and transport mechanisms are still a matter of guesswork. Here we demonstrate that intermittent-contact atomic force microscopy (AFM) can detect the Hall effect in conducting domain walls. Studying YbMnO3 single crystals, we have confirmed that p-type conduction occurs in tail-to-tail charged domain walls. By calibration of the AFM signal, an upper estimate of ∼1 × 1016 cm−3 is calculated for the mobile carrier density in the wall, around four orders of magnitude below that required for complete screening of the polar discontinuity. A carrier mobility of∼50 cm2V−1s−1 is calculated, about an order of magnitude below equivalent carrier mobilities in p-type silicon, but sufficiently high to preclude carrier-lattice coupling associated with small polarons.
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机译:铁电体中特定畴壁处的导电性增强现已成为一种普遍现象。然而,令人惊讶的是,对于传导的最基本方面知之甚少。承运人的类型,密度和机动性尚未确定,运输机制仍然是猜测。在这里,我们证明了间歇接触原子力显微镜(AFM)可以检测传导畴壁中的霍尔效应。研究YbMnO3单晶,我们已经证实p型传导发生在尾到尾带电畴壁中。通过对AFM信号进行校准,可以计算出壁中移动载流子密度的大约1×10 16 sup> cm -3 sup>的上限,大约在以下四个数量级完全筛选极间断点所需的时间。计算出约50 mobilitycm 2 sup> V -1 sup> s -1 sup>的载流子迁移率,大约比p-中的等效载流子迁移率低一个数量级。硅,但足够高以排除与小极化子相关的载流子-晶格耦合。
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