Infrared-Induced Sluggish Dynamics in the GeSbTe Electron Glass

The electron-glass dynamics of Anderson-localized GeSbTe films is dramatically slowed down following a brief infrared illumination that increases the system carrier concentration (and thus its conductance). These results demonstrate that the dynamics exhibited by electron glasses is more sensitive to carrier concentration than to disorder. In turn, this seems to imply that many-body effects such as the orthogonality catastrophe must play a role in the sluggish dynamics observed in the intrinsic electron glasses.

Figure 1

The two-dip experiment performed on a ${\mathrm{GeSb}}_x{\mathrm{Te}}_y$ film with $R_{\square }=4.4M\mathrm{\Omega }$ in the dark state. Curves are shifted for clarity. The dotted line depicts the underlying thermodynamic density of states. The inset shows the time dependence of the old and new memory dips (see text for details). Sample lateral dimensions are $W=1\mathrm{mm}$, $L=\frac{1}{2}\mathrm{mm}$.

Figure 2

The time dependence of the conductance before, during, and after exposing the sample (as in Fig. 1) to infrared (3 sec at 1 mA). The inset depicts fitting the relaxation of $G$ in the induced PPC state. Fitting parameters are $A=3.375$, $\tau =2\times {10}^8\sec$, $\beta =0.1$.

Figure 3

The two-dip experiment as in Fig. 1 but after the sample is put in its PPC state. Curves are shifted for clarity. The dashed lines are guides for the eye.

Figure 4

Conductance vs gate-voltage sweeps for the sample taken at the indicated times after the sample was exposed to infrared radiation (using the protocol described in Fig. 2). The inset shows the corresponding MD obtained by subtracting a straight line from the respective $G(V_g)$ trace (with corresponding labels as in the main figure). The blue circles are data points for the 12-min MD multiplied by a constant (1.157) to match the $\mathrm{\Delta }G$ value of the 9-h trace at equilibrium $V_g$. This illustrates that the 12-min MD is wider than the long-time value [these MD’s appear to coincide at the end points of the $V_g$-measured range “by construction,” due to the way they were obtained from the composite $G(V_g)$].