Control over minivalley polarization and interlayer coupling is demonstrated in double bilayer graphene twisted with an angle of 2.37°. This intermediate angle is small enough for the minibands to form and large enough such that the charge carrier gases in the layers can be tuned independently. Using a dual-gated geometry we identify and control all possible combinations of minivalley polarization via the population of the two bilayers. An applied displacement field opens a band gap in either of the two bilayers, allowing us to even obtain full minivalley polarization. In addition, the carriers, formerly separated by their minivalley character, are mixed by tuning through a Lifshitz transition, where the Fermi surface topology changes. The high degree of control over the minivalley character of the bulk charge transport in twisted double bilayer graphene offers new opportunities for realizing valleytronics devices such as valley valves, filters, and logic gates.

中文翻译：

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双层双层石墨烯中的最小谷和层控制相结合

在双层双层石墨烯中以2.37°的角度扭曲证明了对微谷极化和层间耦合的控制。该中间角足够小以形成微带并且足够大，使得可以独立地调节层中的载流子气体。使用双门几何结构，我们可以通过两个双层的填充来识别和控制微谷极化的所有可能组合。施加的位移场会在两个双层中的任何一个中打开一个带隙，使我们甚至可以获得完全的微谷极化。此外，以前通过微谷特征分开的载波通过在费米表面拓扑发生变化的Lifshitz跃迁进行调谐而混合在一起。