Proximity Effect Induced Electronic Properties of Graphene on Bi2Te2Se

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• 作者：Paengro Lee ; Kyung-Hwan Jin ; Si Jin Sung ; Jin Gul Kim ; Min-Tae Ryu ; Hee-Min Park ; Seung-Hoon Jhi ; Namdong Kim ; Yongsam Kim ; Seong Uk Yu ; Kwang S. Kim ; Do Young Noh ; Jinwook Chung
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：9
• 期：11
• 页码：10861-10866
• 全文大小：410K
• ISSN：1936-086X

文摘

We report that the 蟺-electrons of graphene can be spin-polarized to create a phase with a significant spin鈥搊rbit gap at the Dirac point (DP) using a graphene-interfaced topological insulator hybrid material. We have grown epitaxial Bi₂Te₂Se (BTS) films on a chemical vapor deposition (CVD) graphene. We observe two linear surface bands from both the CVD graphene notably flattened and BTS coexisting with their DPs separated by 0.53 eV in the photoemission data measured with synchrotron photons. We further demonstrate that the separation between the two DPs, 螖_D鈥揇, can be artificially fine-tuned by adjusting the amount of Cs atoms adsorbed on the graphene to a value as small as 螖_D鈥揇 = 0.12 eV to find any proximity effect induced by the DPs. Our density functional theory calculation shows the opening of a spin鈥搊rbit gap of 鈭?0 meV in the 蟺-band, enhanced by 3 orders of magnitude from that of a pristine graphene, and a concomitant phase transition from a semimetallic to a quantum spin Hall phase when 螖_D鈥揇 鈮?0.20 eV. We thus present a practical means of spin-polarizing the 蟺-band of graphene, which can be pivotal to advance graphene-based spintronics.