Visualization of defects in single-crystal and thin-film <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>PdCoO</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math> using aberration-corrected scanning transmission electron microscopy

Single-crystal delafossite ${\mathrm{PdCoO}}_{2}$ is known to have an extremely low intrinsic impurity concentration of \ensuremath{\sim}0.001%, demonstrating extraordinarily high conductivity with a mean free path \ensuremath{\sim}20 \ensuremath{\mu}m at temperatures. However, when grown as thin films, the resistivity room temperature increases by factor 3--80 times, depending on film thickness. Using scanning transmission electron microscopy, we identify different classes defects for single crystal vs epitaxial film. The dominant defect single-crystal found be ribbonlike defects. For types arising in films mainly due substrate termination that disrupt lateral connectivity conducting planes. Our results are consistent crystals and increased electrical compared crystals, suggesting selecting proper substrate, improving surface quality, reducing step density keys enhance quality utilizing platform future applications.