Electrically tunable transverse magnetic focusing in graphene
Electrically tunable transverse magnetic focusing in graphene
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DOI：
10.1038/nphys2549
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发表时间：
2013-04-01
期刊：
影响因子：
19.6
通讯作者：
Jarillo-Herrero, Pablo
中科院分区：
文献类型：
--
作者：
Taychatanapat, Thiti;Watanabe, Kenji;Jarillo-Herrero, Pablo
尽管由于原子核存在不均匀的库仑势，但周期性晶格中的电子可以在宏观距离上无散射地传播（1）。电子的这种弹道运动允许使用横向磁场来聚焦电子（2）。这种现象被称为横向磁聚焦（transverse magnetic focusing，简称TMF），已被用于研究金属（3）和半导体异质结构（4）的费米表面，以及研究Andreev反射（3）和自旋轨道相互作用（5），并检测复合费米子（6，7）。在这里，我们报告的高迁移率的单层，双层和三层石墨烯器件的实验观察。调整石墨烯载流子密度的能力使我们能够从空穴到电子状态连续地研究石墨烯，并分析由此产生的聚焦扇。此外，通过对三层石墨烯施加横向电场，我们使用电子能谱作为弹道电子能谱方法来研究材料电子结构的受控变化。最后，我们证明了石墨烯中的石墨烯在高达300 K的温度下仍然存在，这是迄今为止报道的任何系统的最高温度，为基于电子光学的新室温应用打开了大门。
Electrons in a periodic lattice can propagate without scattering for macroscopic distances despite the presence of the non-uniform Coulomb potential due to the nuclei(1). Such ballistic motion of electrons allows the use of a transverse magnetic field to focus electrons(2). This phenomenon, known as transverse magnetic focusing (TMF), has been used to study the Fermi surface of metals(3) and semiconductor heterostructures(4), as well as to investigate Andreev reflection(3) and spin-orbit interaction(5), and to detect composite fermions(6,7). Here we report on the experimental observation of TMF in high-mobility mono-, bi-and tri-layer graphene devices. The ability to tune the graphene carrier density enables us to investigate TMF continuously from the hole to the electron regime and analyse the resulting focusing fan. Moreover, by applying a transverse electric field to tri-layer graphene, we use TMF as a ballistic electron spectroscopy method to investigate controlled changes in the electronic structure of a material. Finally, we demonstrate that TMF survives in graphene up to 300 K, by far the highest temperature reported for any system, opening the door to new room-temperature applications based on electron-optics.