NPG Asia Materials 2017-07-01

Van der Waals epitaxy between the highly lattice mismatched Cu-doped FeSe and Bi2Te3

Arsham Ghasemi, Demie Kepaptsoglou, Pedro L Galindo, Quentin M Ramasse, Thorsten Hesjedal, Vlado K Lazarov

Index: 10.1038/am.2017.111

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Abstract

We present a structural and density functional theory study of FexCu1−xSe within the three-dimensional topological insulator Bi2Te3. The FexCu1−xSe inclusions are single-crystalline and epitaxially oriented with respect to the Bi2Te3 thin film. Aberration-corrected scanning transmission electron microscopy and electron energy loss spectroscopy show an atomically sharp FeICu1−xSe/Bi2Te3 interface. The FexCu1−xSe/Bi2Te3 interface is determined by Se–Te bonds and no misfit dislocations are observed, despite the different lattice symmetries and large lattice mismatch of ~19%. First-principle calculations show that the large strain at the FexCu1−xSe/Bi2Te3 interface can be accommodated by van der Waals-like bonding between Se and Te atoms.