Phonon-induced electronic relaxation in a strongly correlated system: the Sn/Si(111) $(\sqrt{3}\times \sqrt{3})$ adlayer revisited

Abstract

The ordered adsorbate layer Sn/Si(111) $(\sqrt{3}\times \sqrt{3})$ with coverage of one third of a monolayer is considered as a realization of strong electronic correlation in surface physics. Our theoretical analysis shows that electron-hole pair excitations in this system can be long-lived, up to several hundred nanoseconds, since the decay into surface phonons is found to be a highly non-linear process. We combine first-principles calculations with help of a hybrid functional (HSE06) with modeling by a Mott-Hubbard Hamiltonian coupled to phononic degrees of freedom. The calculations show that the Sn/Si(111) $(\sqrt{3}\times \sqrt{3})$ surface is insulating and the two Sn-derived bands inside the substrate band gap can be described as the lower and upper Hubbard band in a Mott-Hubbard model with $U=0.75$eV. Furthermore, phonon spectra are calculated with particular emphasis on the Sn-related surface phonon modes. The calculations demonstrate that the adequate treatment of electronic correlations leads to a stiffening of the wagging mode of neighboring Sn atoms; thus, we predict that the onset of electronic correlations at low temperature should be observable in the phonon spectrum, too. The deformation potential for electron-phonon coupling is calculated for selected vibrational modes and the decay rate of an electron-hole excitation into multiple phonons is estimated, substantiating the very long lifetime of these excitations.

9 pages, 9 figures

References in corpus (3)

• Probing many-body dynamics on a 51-atom quantum simulator
• Triangular Mott-Hubbard Insulator Phases of Sn/Si(111) and Sn/Ge(111) Surfaces
• Spin-orbit coupling and magnetic interactions in Si(111):{C,Si,Sn,Pb}

Cited by in corpus (4)

• Evidence for chiral superconductivity on a silicon surface
• Superconductivity in a hole-doped Mott-insulating triangular adatom layer on a silicon surface
• Electronic structure, spin-orbit interaction and electron-phonon coupling of triangular adatom lattices on semiconductor substrates
• The electronic structure of a doped Mott-Hubbard surface