Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India.
Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005, India.
Nat Commun. 2017 Feb 20;8:14518. doi: 10.1038/ncomms14518.
Quantum Hall effect provides a simple way to study the competition between single particle physics and electronic interaction. However, electronic interaction becomes important only in very clean graphene samples and so far the trilayer graphene experiments are understood within non-interacting electron picture. Here, we report evidence of strong electronic interactions and quantum Hall ferromagnetism seen in Bernal-stacked trilayer graphene. Due to high mobility ∼500,000 cmVs in our device compared to previous studies, we find all symmetry broken states and that Landau-level gaps are enhanced by interactions; an aspect explained by our self-consistent Hartree-Fock calculations. Moreover, we observe hysteresis as a function of filling factor and spikes in the longitudinal resistance which, together, signal the formation of quantum Hall ferromagnetic states at low magnetic field.
量子霍尔效应为研究单粒子物理和电子相互作用之间的竞争提供了一种简单的方法。然而，电子相互作用只有在非常干净的石墨烯样品中才变得重要，到目前为止，三层石墨烯的实验都是在非相互作用电子图像的框架内理解的。在这里，我们报告了在伯纳尔堆叠的三层石墨烯中观察到的强电子相互作用和量子霍尔铁磁体的证据。由于我们的器件中的迁移率高达 500000cmVs，与之前的研究相比，我们发现了所有对称性破缺的状态，并且相互作用增强了 Landau 能级间隙；这一方面可以通过我们的自洽 Hartree-Fock 计算来解释。此外，我们观察到作为填充因子的函数的滞后和纵向电阻中的尖峰，这两者共同表明在低磁场下形成了量子霍尔铁磁态。
