Surface structure of cleaved (001) USb₂ single crystal

Abstract

We have achieved what we believe to be the first atomic resolution scanning tunneling microscopy (STM) images for a uranium compound USb₂ taken at room temperature. The a, b, and c lattice parameters in the images confirm that the tetragonal USb₂ crystals cleave on the (001) basal plane as expected. Our calculations indicate a symmetric cut between Sb planes to be the most favorable cleavage plane and U atoms to be responsible for most of the density of states measured by STM. Since the spacing between Sb atoms and between U atoms is the same, STM topography alone cannot unambiguously identify the surface atom species.

Keywords:

• USb₂
• surface
• DFT
• STM
• UHV
• f electrons

Acknowledgements

We would like to thank J.L. Smith for his insights and many wonderful discussions. We thank Laila Mattos for passing on her cleaving expertise. We also like to thank US DOE and NNSA for the support of this work at Los Alamos National Laboratory and at Stanford (SLAC contract DE-AC02-76SF00515).