Mashhadi Soudabeh, Kim Youngwook, Kim Jeongwoo, Weber Daniel, Taniguchi Takashi, Watanabe Kenji, Park Noejung, Lotsch Bettina, Smet Jurgen H, Burghard Marko, Kern Klaus
Max-Planck-Institut für Festkörperforschung , Heisenbergstrasse 1 , D-70569 Stuttgart , Germany.
Department of Emerging Materials Science , DGIST , 333 Techno-Jungang-daero, Hyeonpung-Myun, Dalseong-Gun, Daegu 42988 Korea.
Nano Lett. 2019 Jul 10;19(7):4659-4665. doi: 10.1021/acs.nanolett.9b01691. Epub 2019 Jun 26.
Proximity effects induced in the two-dimensional Dirac material graphene potentially open access to novel and intriguing physical phenomena. Thus far, the coupling between graphene and ferromagnetic insulators has been experimentally established. However, only very little is known about graphene's interaction with antiferromagnetic insulators. Here, we report a low-temperature study of the electronic properties of high quality van der Waals heterostructures composed of a single graphene layer proximitized with α-RuCl. The latter is known to become antiferromagnetically ordered below 10 K. Shubnikov-de Haas oscillations in the longitudinal resistance together with Hall resistance measurements provide clear evidence for a band realignment that is accompanied by a transfer of electrons originally occupying the graphene's spin degenerate Dirac cones into α-RuCl band states with in-plane spin polarization. Left behind are holes in two separate Fermi pockets, only the dispersion of one of which is distorted near the Fermi energy due to spin selective hybridization with these spin polarized α-RuCl band states. This interpretation is supported by our density functional theory calculations. An unexpected damping of the quantum oscillations as well as a zero-field resistance upturn close to the Néel temperature of α-RuCl suggest the onset of additional spin scattering due to spin fluctuations in the α-RuCl.
二维狄拉克材料石墨烯中诱导的近邻效应可能会带来新的有趣物理现象。到目前为止，石墨烯与铁磁绝缘体之间的耦合已通过实验得到证实。然而，关于石墨烯与反铁磁绝缘体的相互作用，人们所知甚少。在此，我们报告了对由单层石墨烯与α-RuCl近邻组成的高质量范德华异质结构的电子性质的低温研究。已知后者在10 K以下会发生反铁磁有序。纵向电阻中的舒布尼科夫-德哈斯振荡以及霍尔电阻测量为能带重新排列提供了明确证据，这种能带重新排列伴随着原本占据石墨烯自旋简并狄拉克锥的电子转移到具有面内自旋极化的α-RuCl能带态。留下的是两个独立费米口袋中的空穴，其中只有一个的色散在费米能量附近因与这些自旋极化的α-RuCl能带态的自旋选择性杂化而发生扭曲。我们的密度泛函理论计算支持了这一解释。量子振荡的意外阻尼以及接近α-RuCl奈尔温度时的零场电阻上升表明，由于α-RuCl中的自旋涨落，额外的自旋散射开始出现。
