Spontaneous Valley Polarization of Itinerant Electrons
Spontaneous Valley Polarization of Itinerant Electrons
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流动电子的自发谷极化
DOI：
10.1103/physrevlett.127.116601
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发表时间：
2021
影响因子：
8.6
通讯作者：
Shayegan, M.
中科院分区：
文献类型：
--
作者：
Hossain, Md. S.;Ma, M. K.;Villegas-Rosales, K. A.;Chung, Y. J.;Pfeiffer, L. N.;West, K. W.;Baldwin, K. W.;Shayegan, M.
基于电子的自旋而不是其电荷自由度的存储器或晶体管器件提供了某些独特的优点，并且构成了自旋电子学的基石。近年来出现了一个新的领域，谷电子学，它试图利用电子的谷指数，而不是它的自旋。在这一探索中的一个重要组成部分将是以方便的方式控制谷指数的能力。在这里，我们表明，谷极化可以从零切换到1的密度的一个小的减少，简单地调整由栅极偏置，在一个二维的电子系统。这种现象，这是类似于布洛赫自旋铁磁性，出现根本上是由于电子-电子相互作用的巡回，稀电子系统。从本质上讲，动能有利于电子在可用谷上的均匀分布，而电子之间的相互作用则倾向于低于临界密度的单谷占有率。我们观察到的栅极偏置调谐过渡是伴随着一个突然的，双重的样品电阻的变化，使潜在的valleytronic晶体管器件的应用感兴趣的现象。我们的观察在一个非常简单的实验中构成了谷电子学的典型演示。
Memory or transistor devices based on an electron’s spin rather than its charge degree of freedom offer certain distinct advantages and comprise a cornerstone of spintronics. Recent years have witnessed the emergence of a new field, valleytronics, which seeks to exploit an electron’s valley index rather than its spin. An important component in this quest would be the ability to control the valley index in a convenient fashion. Here we show that the valley polarization can be switched from zero to 1 by a small reduction in density, simply tuned by a gate bias, in a two-dimensional electron system. This phenomenon, which is akin to Bloch spin ferromagnetism, arises fundamentally as a result of electron-electron interaction in an itinerant, dilute electron system. Essentially, the kinetic energy favors an equal distribution of electrons over the available valleys, whereas the interaction between electrons prefers single-valley occupancy below a critical density. The gate-bias-tuned transition we observe is accompanied by a sudden, twofold change in sample resistance, making the phenomenon of interest for potential valleytronic transistor device applications. Our observation constitutes a quintessential demonstration of valleytronics in a very simple experiment.