Superconductivity in a two monolayer thick indium film on Si(111)√3 x √3-B

Two-monolayer-thick In film with a root 7 x root 3-rect structure is known to show superconductivity at 3.18 K on the Si(111)7x7 substrate. We synthesized the root 7 x root 3-In-rect film on the Si(111)root 3 x root 3-B substrate and found that it also became a superconductor at T-c = 2.38 K. The In film on the root 3-B substrate showed the two-dimensional free-electron-like circular Fermi surface as on the 7 x 7 substrate. However, the butterfly-wing-like shape contour at the Fermi surface was found to be shifted and enlarged on the root 3-B substrate. Density functional calculations revealed that it was caused by the difference of the substrate. T-c on the root 3-B substrate was considered to be identical to that on the 7 x 7 substrate in consideration of the recently reported surface defect density dependence of T-c. These results indicated that the interaction with the substrate does not play a crucial role in the superconductivity of the two-monolayer-thick In film.

Automated summary

Both the root 7 x root 3-In-rect film and the two-monolayer-thick In film on Si substrates showed superconductivity, with a similar Fermi surface contour but slightly different shapes. The interaction between the substrate and the films was found to have a minimal effect on the superconductivity, as the transition temperature T-c remained the same.