Figure 3
Mechanical manipulation of quantum interference and thermoelectric effect for a weakly strained Au atomic junction. (a,b) Simplified picture of the quantum interference in Au atomic junctions. An electron wave enters from the left and passes through the atomic junction (shown in green) once, or three times after scattering from defects shown in grey. The wave accumulates different phase shifts Δφ = 4π or 4.5π as it passes through the unstrained (a) or strained (b) atomic junction, respectively. In both cases the two partial waves exiting to the right interfere constructively (transmission is maximal) because states with suitably differing energies and de Broglie wavelengths (λ and λ’) outside of the junction were chosen. (c,d) Model Au geometries near the junction. In (c) the distance between the two central Au atoms in the junction is 2.75 Å. It has been reduced to 2.63 Å in (d). Insets: Typical calculated wave functions Re(<6 s|Ψ>) in the junctions. Δφ = 2.23π and 2.36π for (c) and (d) respectively. (e,f) Calculated Landauer electron transmission probabilities τ(E) (ignoring spin) through the structures (c,d) vs. electron energy E. Peaks of τ(E) are at lower energies in (f) than (e). Conductances are given by G = G 0 τ(E F) = 0.985 G 0 and 1.03 G 0 in (e) and (f), where G 0 = 2e 2/h. (g,h) ΔV/ΔT defined by Eq. 1 vs. energy E calculated at a mean temperature of 27 K for the structures (c,d). At the Fermi level, ΔV = +2.99 μV and −4.95 μV for ΔT = 16 K for (g) and (h).
