C60 capping of metallic 2D Tl-Au compound with preservation of its basic properties at the buried interface

[Display omitted] •C60 fullerite film was grown epitaxially on (Tl, Au)/Si(111)7×7 reconstruction.•Atomic structure of (Tl, Au)/Si(111) reconstruction is preserved at buried interface.•C60/(Tl, Au)/Si(111) sandwich displays the properties of 2D metal system.•It shows spin-split surface-state bands and metallic conductivity with WAL effect. So-called metal-induced silicon reconstructions (i.e., metal films of monolayer or submonolayer thickness epitaxially grown on single-crystal silicon substrates in ultra-high vacuum) represent a specific class of low-dimensional advanced materials with potential prospects for electronic and spintronic applications. However, they are highly vulnerable to air and, thus, require protective capping. Finding a suitable material is a challenging task, since, in general, the metal-induced reconstructions are vulnerable also to overgrowth of solid layers. In the present study, we have found that C60 fullerite film shows up as a proper capping layer for the (Tl, Au)/Si(111)7 × 7 compound reconstruction. Due to a perfect non-distractive epitaxial C60 overgrowth, the metallic Tl-Au compound preserves at the deeply buried interface its atomic structure and all basic electronic properties, including spin-splitting of surface-state bands and conductivity of metallic type with a weak antilocalization effect.