Inelastic scattering in metal-H2-metal junctions

Abstract

We present first-principles calculations of the dI/dV characteristics of an H2 molecule sandwiched between Au and Pt electrodes in the presence of electron-phonon interactions. The conductance is found to decrease by a few percentage at threshold voltages corresponding to the excitation energy of longitudinal vibrations of the H2 molecule. In the case of Pt electrodes, the transverse vibrations can mediate transport through otherwise non-transmitting Pt d-channels leading to an increase in the differential conductance even though the hydrogen junction is characterized predominately by a single almost fully open transport channel. In the case of Au, the transverse modes do not affect the dI/dV because the Au d-states are too far below the Fermi level. A simple explanation of the first-principles results is given using scattering theory. Finally, we compare and discuss our results in relation to experimental data.

First-principles quantum transport with electron-vibration interactions: A maximally localized Wannier functions approach

“…Using multieigenchannel analysis based on scattering theory, we have identified that out-of-plane and in-plane vibrational motions lead to conductance jumps and drops respectively. This analysis on the simultaneous occurrence of conductance jumps and drops is consistent with recently reported calculation 52 . In the second application, where cumulene wires are replaced by realistic CNT electrodes, we have focused on the decay rates of molecular vibrations and nonequilibrium vibrational populations.…”

“…This simultaneous occurrence can be understood from scattering theory and transmission eigenchannels 54,55 , following Ref. 52 . As seen in Fig.6, let us consider an electron injected from the left electrode on a left-incident ith eigenchannel |Ψ i L at energy ε.…”

Identification of vibration modes in single-molecule junctions by strong inelastic signals in noise

“…Junction 3: (d) differential conductance showing a step-up taken before (black) and after (red) the noise measurement. This is similar to a step up case discussed in Kristensen et al 28 (e) Usual IETS spectrum of the junction showing weak detection of the vibrational modes of the junction (black arrows). (f ) The IENS-3 spectrum showing enhanced peak corresponding to the positions of inelastic interactions (black arrow).…”

“…4(d-f ), we note first that the differential conductance shows a step-up at energies close to the energy of the vibrons. This is something which has not been reported in experiments before, but such a possibility has already been discussed theoretically by Kristensen et al 28 A detailed discussion on this is given in the ESI † along with other experimental data-sets. However, important to note is that even in this example the IETS spectra ( Fig.…”

Vibrationally mediated control of single-electron transmission in weakly coupled molecule-metal junctions

“…Analysis of model Hamiltonians [6][7][8][9] have given qualitative insight into the interaction of tunneling electrons with molecular vibrations while DFT-based studies in conjunction with a nonequilibrium Green's-function approach show quantitative agreement with experiments. [10][11][12] Most efforts so far have been directed toward the influence of vibrations on transmission functions and I-V characteristics. In the present paper, we will take a slightly different point of view and partition the electronic transmission function into pieces that involve different vibrational excitations.…”