Vibration signatures of the structural phase transition of Sn/Ge(111) compared to Sn/Si(111)

Halbig, B.; Bass, U.; Geurts, J.; Sanna, Simone

doi:10.1103/physrevb.100.035437

Cited by 4 publications

(3 citation statements)

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“…In addition, our nonspinpolarized PBE calculations show a mode characterized by lateral motion of the Sn atom at 1.67 THz, in agreement with Ref. 15. Remarkably, we find both the FM and the AFM states in a spin-polarized PBE calculation with a (2 √ 3 × √ 3) unit cell to be energetically higher than the NM state, by 10 and 11 meV per Sn atom, respectively.…”

Section: A Phonon and Electron Band Structure From Gga-pbe Calculationssupporting

confidence: 91%

“…For the complementary system Sn/Ge(111), our calculated results are in line with this conclusion: Here, the spin-polarized states are found to be energetically higher than the non-spinpolarized state, which leaves only the displacive rearrangement of the atoms as stabilization mechanism. It is noteworthy that a recent Raman study [15] observed peaks with E symmetry at 2.65 THz for Sn/Si and 1.67 THz for Sn/Ge(111), in addition to some more noisy structures at lower frequencies. Our computed results are in agreement with both experimental values.…”

Section: A Phonon and Electron Band Structure From Gga-pbe Calculationsmentioning

confidence: 88%

“…However, more recent experimental studies found a reconstruction of Sn/Ge(111) again with the smaller ( √ 3 × √ 3) unit cell at temperatures below 30 K that undergoes a transition to an insulating phase upon further cooling [13]. While the Jahn-Teller instability makes itself noticeable in the softening of the corresponding phonon mode showing up as height fluctuations of the surface Sn atoms [14], the effect of strong electronic correlations on the phonon spectrum has received less attention, with the exception of a very recent Raman spectroscopy study [15]. We will show that electronic correlations in Sn/Si(111) ( √ 3 × √ 3) favor a planar geometry and lead to a stiffening of the associated phonon mode.…”

Section: Introductionmentioning

confidence: 99%

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Phonon-induced electronic relaxation in a strongly correlated system: The Sn/Si(111) (3×3) adlayer revisited

Zahedifar

Kratzer

2019

Phys. Rev. B

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The ordered adsorbate layer Sn/Si(111) ( √ 3 × √ 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 electronhole 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) ( √ 3 × √ 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.

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Section: A Phonon and Electron Band Structure From Gga-pbe Calculationssupporting

confidence: 91%

Section: A Phonon and Electron Band Structure From Gga-pbe Calculationsmentioning

confidence: 88%