Structural and electronic properties of Tl films on Ag(111): From (3×3) surface alloy to moiré superstructure

Surface alloys between the heavy metals Bi, Pb, or Sb and noble metals, such as Ag(111), are known for their giant Rashba splitting. Although thallium (Tl) should result in isostructural surface alloys, its structural and electronic properties remained elusive. The authors present here a detailed work on the structural and electronic properties of Tl films epitaxially grown on Ag(111) surfaces. By combining experimental LEED, AES, STM/STS, and IPE with $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ band structure and charge distribution calculations, the $s$,${p}_z$-derived surface state of the TlAg${}₂$ surface alloy is identified, with a weak, but finite, Rashba splitting.