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Unveiling Temperature-Induced Structural Domains and Movement of Oxygen Vacancies in SrTiO3 with Graphene
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2020-11-11 , DOI: 10.1021/acsami.0c15458
Si Chen 1 , Xin Chen 2 , Elisabeth A. Duijnstee 1 , Biplab Sanyal 2 , Tamalika Banerjee 1
Affiliation  

Heterointerfaces coupling complex oxides exhibit coexisting functional properties such as magnetism, superconductivity, and ferroelectricity, often absent in their individual constituent. SrTiO3 (STO), a canonical band insulator, is an active constituent of such heterointerfaces. Temperature-, strain-, or mechanical stress-induced ferroelastic transition leads to the formation of narrow domains and domain walls in STO. Such ferroelastic domain walls have been studied using imaging or transport techniques and, often, the findings are influenced by the choice and interaction of the electrodes with STO. In this work, we use graphene as a unique platform to unveil the movement of oxygen vacancies and ferroelastic domain walls near the STO surface by studying the temperature and gate bias dependence of charge transport in graphene. By sweeping the back gate voltage, we observe antihysteresis in graphene typically observed in conventional ferroelectric oxides. Interestingly, we find features in antihysteresis that are related to the movement of domain walls and of oxygen vacancies in STO. We ascertain this by analyzing the time dependence of the graphene square resistance at different temperatures and gate bias. Density functional calculations estimate the surface polarization and formation energies of layer-dependent oxygen vacancies in STO. This corroborates quantitatively with the activation energies determined from the temperature dependence of the graphene square resistance. Introduction of a hexagonal boron nitride (hBN) layer, of varying thicknesses, between graphene and STO leads to a gradual disappearance of the observed features, implying the influence of the domain walls onto the potential landscape in graphene.

中文翻译:

利用石墨烯揭示SrTiO 3中温度诱导的结构域和氧空位的移动

偶联复合氧化物的异质界面表现出共存的功能特性,例如磁性,超导性和铁电性,通常在它们各自的成分中不存在。钛酸锶3(STO)是规范的带绝缘子,是此类异质界面的有效组成部分。温度,应变或机械应力引起的铁弹性转变会导致在STO中形成狭窄的畴和畴壁。已经使用成像或传输技术研究了此类铁弹性畴壁,并且通常,发现受电极与STO的选择和相互作用的影响。在这项工作中,我们通过研究石墨烯中电荷传输的温度和栅极偏压依赖性,使用石墨烯作为独特的平台来揭示STO表面附近的氧空位和铁弹性畴壁的运动。通过扫描背栅电压,我们观察到了石墨烯中的磁滞现象,而这种现象通常在常规铁电氧化物中观察到。有趣的是 我们发现抗磁滞特性与STO中畴壁的移动和氧空位有关。我们通过分析不同温度和栅极偏压下石墨烯方形电阻的时间依赖性来确定这一点。密度泛函计算可估算STO中依赖于层的氧空位的表面极化和形成能。这定量地证实了由石墨烯方形电阻的温度依赖性所确定的活化能。在石墨烯和STO之间引入厚度可变的六方氮化硼(hBN)层会导致观察到的特征逐渐消失,这意味着畴壁对石墨烯中的潜在景观产生了影响。我们通过分析不同温度和栅极偏压下石墨烯方形电阻的时间依赖性来确定这一点。密度泛函计算可估算STO中依赖于层的氧空位的表面极化和形成能。这定量地证实了由石墨烯方形电阻的温度依赖性所确定的活化能。在石墨烯和STO之间引入厚度可变的六方氮化硼(hBN)层会导致观察到的特征逐渐消失,这意味着畴壁对石墨烯中的潜在景观产生了影响。我们通过分析不同温度和栅极偏压下石墨烯方形电阻的时间依赖性来确定这一点。密度泛函计算可估算STO中依赖于层的氧空位的表面极化和形成能。这定量地证实了由石墨烯方形电阻的温度依赖性所确定的活化能。在石墨烯和STO之间引入厚度可变的六方氮化硼(hBN)层会导致观察到的特征逐渐消失,这意味着畴壁对石墨烯中的潜在景观产生了影响。这定量地证实了由石墨烯方形电阻的温度依赖性所确定的活化能。在石墨烯和STO之间引入厚度可变的六方氮化硼(hBN)层会导致观察到的特征逐渐消失,这意味着畴壁对石墨烯中的潜在景观产生了影响。这定量地证实了由石墨烯方形电阻的温度依赖性所确定的活化能。在石墨烯和STO之间引入厚度可变的六方氮化硼(hBN)层会导致观察到的特征逐渐消失,这意味着畴壁对石墨烯中的潜在景观产生了影响。
更新日期:2020-11-25
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