Collective bulk carrier delocalization driven by electrostatic surface charge accumulation
Collective bulk carrier delocalization driven by electrostatic surface charge accumulation
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DOI：
10.1038/nature11296
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发表时间：
2012-07-26
期刊：
影响因子：
64.8
通讯作者：
Tokura, Y.
中科院分区：
文献类型：
--
作者：
Nakano, M.;Shibuya, K.;Tokura, Y.
在经典晶体管中，电荷载流子的数量以及电导率由外部电压精确控制，从而提供电气开关能力。这个简单但强大的功能对于信息处理技术来说是必不可少的，也为基础物理研究提供了一个平台。由于电荷的数量基本上决定了凝聚态系统的电子相，晶体管的操作使系统的状态发生可逆和等温变化，如电场诱导的铁磁性（2-4）和超导性（5-10）所成功证明的那样。然而，电场的这种效应限于纳米或更小的沟道厚度，这是由于存在的超导费米屏蔽。在这里，我们表明，这种传统的图片不适用于一类材料的特点是固有的集体之间的相互作用的电子和晶格。我们制备了基于二氧化钒的金属-绝缘体-半导体场效应晶体管，二氧化钒是一种强相关材料，具有热驱动的一阶金属-绝缘体转变，远高于室温（17-23），并发现表面的静电充电驱动所有先前局部化的电荷载流子在体材料中运动，导致三维金属基态的出现。电子状态的这种非局部切换通过施加仅约1伏的电压来实现。在电压扫描测量中，金属-绝缘体转变的一阶性质提供了在室温下可操作的非挥发性记忆效应。我们的研究结果展示了一种新的场效应器件，将电场控制的概念扩展到宏观相位控制。
In the classic transistor, the number of electric charge carriers-and thus the electrical conductivity-is precisely controlled by external voltage, providing electrical switching capability. This simple but powerful feature is essential for information processing technology, and also provides a platform for fundamental physics research(1-16). As the number of charges essentially determines the electronic phase of a condensed-matter system, transistor operation enables reversible and isothermal changes in the system's state, as successfully demonstrated in electric-field-induced ferromagnetism(2-4) and superconductivity(5-10). However, this effect of the electric field is limited to a channel thickness of nanometres or less, owing to the presence of Thomas-Fermi screening. Here we show that this conventional picture does not apply to a class of materials characterized by inherent collective interactions between electrons and the crystal lattice. We prepared metal-insulator-semiconductor field-effect transistors based on vanadium dioxide-a strongly correlated-material with a thermally driven, first-order metal-insulator transition well above room temperature(17-23)-and found that electrostatic charging at a surface drives all the previously localized charge carriers in the bulk material into motion, leading to the emergence of a three-dimensional metallic ground state. This non-local switching of the electronic state is achieved by applying a voltage of only about one volt. In a voltage-sweep measurement, the first-order nature of the metal-insulator transition provides a non-volatilememory effect, which is operable at room temperature. Our results demonstrate a conceptually new field-effect device, extending the concept of electric-field control to macroscopic phase control.