论文标题
石墨烯超晶格中棕色扎克费米子的远程弹道运输
Long-range ballistic transport of Brown-Zak fermions in graphene superlattices
论文作者
论文摘要
在量化磁场时，石墨烯超级晶格表现出通常称为Hofstadter蝴蝶的复杂分形光谱。它可以看作是由在每个超级刀位单位单元格的磁通量量子量的有理分数（$ p/q $）量子（$ p/q $）的量化量的量化中产生的。在这里，我们表明，在氮化石墨烯二硝酸盐超级晶格中，棕色扎克·费米斯（Brown-Zak Fermions）可以在10 $^6 $ cm $^2 $ v $^{ - 1} $ s $^{ - 1} $和平均自由路径和超过多个微米的平均自由路径上表现出迁移率。我们的设备的卓越质量使我们可以证明Brown-Zak Minibands为$ 4Q $ $ timess venterate，并且所有脱模（Spin，Valley和Mini-Valley）可以通过以下1K以下的交换交换来提高。我们还发现，售价为$ 1/q $分数的负弯曲电阻，用于分开几微米的电探针。后一个观察结果强调了一个事实，即棕扎克·费米斯（Brown-Zak Fermions）是沿直轨道在高场中传播的bloch准粒子，就像零场中的电子一样。
In quantizing magnetic fields, graphene superlattices exhibit a complex fractal spectrum often referred to as the Hofstadter butterfly. It can be viewed as a collection of Landau levels that arise from quantization of Brown-Zak minibands recurring at rational ($p/q$) fractions of the magnetic flux quantum per superlattice unit cell. Here we show that, in graphene-on-boron-nitride superlattices, Brown-Zak fermions can exhibit mobilities above 10$^6$ cm$^2$V$^{-1}$s$^{-1}$ and the mean free path exceeding several micrometers. The exceptional quality of our devices allows us to show that Brown-Zak minibands are $4q$ times degenerate and all the degeneracies (spin, valley and mini-valley) can be lifted by exchange interactions below 1K. We also found negative bend resistance at $1/q$ fractions for electrical probes placed as far as several micrometers apart. The latter observation highlights the fact that Brown-Zak fermions are Bloch quasiparticles propagating in high fields along straight trajectories, just like electrons in zero field.
