2D system incorporating perforated Mg sheet sandwiched between Pb layer and Si(111)

We synthesized and characterized a new (6 x 6)-periodical 2D compound layer consisting of a Mg network sandwiched between a Pb atomic layer and Si(111) substrate. Angle-resolved photoelectron spectroscopy revealed the close similarity of its electronic structure with that typical for the Pb/Si(111) system. As a result of Mg intercalation, 0.45 eV band bending takes place due to electron doping from Mg (1.27 electron per atom). The electron-phonon coupling constant lambda is enhanced (2.54 +/- 0.1) compared to the pristine Pb/Si(111) monolayer (0.58 +/- 0.1) as derived from temperature-dependent ARPES measurements of the lifetime broadening. Four-point probe transport measurements revealed the abrupt decrease of surface resistance that disappeared in the presence of a magnetic field. It might be an indication of superconducting phase transition. Although we were unable to observe a zero-resistance state and hence to measure T-c directly, we estimated the possible superconducting critical temperature T-c = 1.15 K using the Aslamazov-Larkin correction. This value is close to 1.1 K for the case of pristine Pb/Si(111) system.

Automated summary

We have successfully synthesized and characterized a new 2D compound consisting of a magnesium network sandwiched between a lead atomic layer and a silicon (111) substrate. The electronic structure of this compound is similar to that of the Pb/Si(111) system. The presence of magnesium intercalation leads to band bending and an enhancement in the electron-phonon coupling constant. Our measurements of surface resistance suggest the occurrence of a superconducting phase transition and we estimated the critical temperature of superconductivity.