Ballistic miniband conduction in a graphene superlattice
Ballistic miniband conduction in a graphene superlattice
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DOI：
10.1126/science.aaf1095
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发表时间：
2016-09-30
期刊：
影响因子：
56.9
通讯作者：
Goldhaber-Gordon, David
中科院分区：
文献类型：
--
作者：
Lee, Menyoung;Wallbank, John K.;Goldhaber-Gordon, David
长周期人工晶格的合理设计会产生简单固体中无法实现的效果。高度对准的石墨烯/六方氮化硼（h-BN）异质结构中的莫尔图案是具有高电子迁移率和不寻常的电子分散的横向超晶格，其能带边缘和鞍点可以通过静电门控到达。我们研究了电子的动态莫尔微带通过测量相邻的局部接触在磁场中，被称为横向电子聚焦效应之间的弹道输运。在低温下，我们观察到的焦散线跳跃轨道延伸超过数百个超晶格周期，逆转的回旋革命连续的迷你带，和故障附近的回旋运动货车霍韦奇点。在高温下，电子-电子碰撞抑制聚焦。探测这种微带传导特性对于在超晶格器件中设计新颖的输运行为是必要的。
Rational design of long-period artificial lattices yields effects unavailable in simple solids. The moire pattern in highly aligned graphene/hexagonal boron nitride (h-BN) heterostructures is a lateral superlattice with high electron mobility and an unusual electronic dispersion whose miniband edges and saddle points can be reached by electrostatic gating. We investigated the dynamics of electrons in moire minibands by measuring ballistic transport between adjacent local contacts in a magnetic field, known as the transverse electron focusing effect. At low temperatures, we observed caustics of skipping orbits extending over hundreds of superlattice periods, reversals of the cyclotron revolution for successive minibands, and breakdown of cyclotron motion near van Hove singularities. At high temperatures, electron-electron collisions suppress focusing. Probing such miniband conduction properties is a necessity for engineering novel transport behaviors in superlattice devices.