Figure 1

(Color online) (a) Schematic of SMT measurement setup. (b) Transport path for conduction electrons in SMT device. Traces of $dI/dV$ vs $V$ for several temperatures (c) from 1.8 K (tallest/black) to 53 K (shortest/maroon) for device A, using complex 1, and (d) from 1.8 K (tallest/black) to 46 K (shortest/maroon) for device B, using ${\text{C}}_{60}$. Amplitude of Kondo resonance decreases with increasing temperature. Insets: schematic of (c) complex 1 and (d) ${\text{C}}_{60}$. (e) $dI/dV$ vs $V$ at $T=1.8\text{K}$ for two samples, demonstrating the disparate Kondo temperatures associated with different devices. Device C (blue) contains a ${\text{C}}_{60}$ molecule and D (red) contains complex 1. Note that the respective background contributions to the measured conductance have not been subtracted from the plots in (c)–(e). (f) Fit of equilibrium conductance versus temperature for devices A–D, using Eq. (1), yielding $T_K\approx 52$, 43, 35, and 105 K, respectively.Reuse & Permissions

Figure 2

(Color online) Extracted values of the scaling coefficient (a) $\alpha$ and (b) $\gamma$ for each device. Open blue circles correspond to devices with complex 1. Filled red circles correspond to devices with ${\text{C}}_{60}$. Dashed gray line indicates average value. Samples are numbered in order of increasing $T_K$.Reuse & Permissions

Figure 3

(Color online) Conductance as a function of $V$ for [(a) and (b)] $T/T_K\lesssim 1.0$ and (c) $T/T_K\lesssim 0.65$, corresponding to devices A, C, and D from Figs. 1c, 1e, respectively. $G_b$ has been subtracted off. (d) Scaled conductance, $\Delta G/{\tilde{\alpha }}_V$, versus ${\left(eV/k_B{T}_K\right)}^2$ for devices A–D, where $\Delta G=\left[1-G\left(T,V\right)/G\left(T,0\right)\right]$. The data from (a)–(c) are plotted here, along with the analogous data set from device B, using the average extracted values of the scaling coefficients. The solid black line represents the associated universal curve. The color bar in (b) pertains to all four figures.Reuse & Permissions