（中性點(diǎn)不接地系統(tǒng)中的電容電流）

知社·今日

1861年，麥克斯韋構(gòu)想了位移電流的概念，完善了電動(dòng)力學(xué)定律，并使利用位移電流的器件得以實(shí)現(xiàn)。雖然近來致力于疇的研究蓬勃興起，疇在化合物中的相應(yīng)電導(dǎo)率也有探討，但目前尚不清楚這種位移電流是否會(huì)在有疇鐵系統(tǒng)中引起大的固有交流電流，同時(shí)人們也很難確定驅(qū)動(dòng)直流疇壁導(dǎo)電的機(jī)制。來自美國阿肯色州立大學(xué)和俄羅斯南聯(lián)邦大學(xué)的Sergey Prosandeev等使用數(shù)值模型表明，高頻疇壁電導(dǎo)可能發(fā)生在多鐵鉍鐵氧體中，鉍鐵氧體的疇壁具有較高的交流電導(dǎo)率，疇壁的固有物理性質(zhì)決定了高頻疇壁電導(dǎo)。根據(jù)他們的預(yù)測，這個(gè)疇壁導(dǎo)電機(jī)制可能為千兆赫電子系統(tǒng)的開發(fā)提供更強(qiáng)大的平臺(tái)。

該文近期發(fā)表于npj Computational Materials 4:8(2018); doi:10.1038/s41524-018-0066-y。英文標(biāo)題與摘要如下，點(diǎn)擊閱讀原文可以自由獲取論文PDF。

Displacement Current in Domain Walls of Bismuth Ferrite

Sergey Prosandeev,Yurong Yang,Charles Paillard& L. Bellaiche

Abstract In 1861, Maxwell conceived the idea of the displacement current, which then made laws of electrodynamics more complete and also resulted in the realization of devices exploiting such displacement current. Interestingly, it is presently unknown if such displacement current can result in large intrinsic ac current in ferroic systems possessing domains, despite the flurry of recent activities that have been devoted to domains and their corresponding conductivity in these compounds. Here, we report first-principles-based atomistic simulations that predict that the transverse (polarization-related) displacement currents of 71° and 109° domains in the prototypical BiFeO3multiferroic material are significant at the walls of such domains and in the GHz regime, and, in fact, result in currents that are at least of the same order of magnitude than previously reported dc currents (that are likely extrinsic in nature and due to electrons). Such large, localized and intrinsic ac currents are found to originate from low-frequency vibrations at the domain walls, and may open the door to the design of novel devices functioning in the GHz or THz range and in which currents would be confined within the domain wall.

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