Supercell formation in epitaxial rare-earth ditelluride thin films

Kavli Affiliate: David A. Muller

| First 5 Authors: Adrian Llanos, Salva Salmani-Rezaie, Jinwoong Kim, Nicholas Kioussis, David A. Muller

| Summary:

Square net tellurides host an array of electronic ground states and commonly
exhibit charge-density-wave ordering. Here we report the epitaxy of
DyTe$_{2-delta}$ on atomically flat MgO (001) using molecular beam epitaxy.
The films are single phase and highly oriented as evidenced by transmission
electron microscopy and X-ray diffraction measurements. Epitaxial strain is
evident in films and is relieved as the thickness increases up to a value of
approximately 20 unit cells. Diffraction features associated with a supercell
in the films are resolved which is coupled with Te-deficiency. First principles
calculations attribute the formation of this defect lattice to nesting
conditions in the Fermi surface, which produce a periodic occupancy of the
conducting Te square-net, and opens a band gap at the chemical potential. This
work establishes the groundwork for exploring the role of strain in tuning
electronic and structural phases of epitaxial square-net tellurides and related
compounds.

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