A novel artificial condensed matter lattice and a new platform for one-dimensional topological phases

13 Mar 2017  ·  Belopolski Ilya, Xu Su-Yang, Koirala Nikesh, Liu Chang, Bian Guang, Strocov Vladimir N., Chang Guoqing, Neupane Madhab, Alidoust Nasser, Sanchez Daniel, Zheng Hao, Brahlek Matthew, Rogalev Victor, Kim Timur, Plumb Nicholas C., Chen Chaoyu, Bertran François, Fèvre Patrick Le, Taleb-Ibrahimi Amina, Asensio Maria-Carmen, Shi Ming, Lin Hsin, Hoesch Moritz, Oh Seongshik, Hasan M. Zahid ·

Engineered lattices in condensed matter physics, such as cold atom optical lattices or photonic crystals, can have fundamentally different properties from naturally-occurring electronic crystals. Here, we report a novel type of artificial quantum matter lattice... Our lattice is a multilayer heterostructure built from alternating thin films of topological and trivial insulators. Each interface within the heterostructure hosts a set of topologically-protected interface states, and by making the layers sufficiently thin, we demonstrate for the first time a hybridization of interface states across layers. In this way, our heterostructure forms an emergent atomic chain, where the interfaces act as lattice sites and the interface states act as atomic orbitals, as seen from our measurements by angle-resolved photoemission spectroscopy (ARPES). By changing the composition of the heterostructure, we can directly control hopping between lattice sites. We realize a topological and a trivial phase in our superlattice band structure. We argue that the superlattice may be characterized in a significant way by a one-dimensional topological invariant, closely related to the invariant of the Su-Schrieffer-Heeger model. Our topological insulator heterostructure demonstrates a novel experimental platform where we can engineer band structures by directly controlling how electrons hop between lattice sites. read more

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Materials Science