Figure 1

Schematic diagrams of current-voltage ($I\mathrm{\text{−}}V$) curves for two resistance switching (RS) phenomena: (a) unipolar memory RS and (b) unipolar threshold RS. Unipolar memory RS can have two resistance states without applied $V$: a low resistance state (LRS) and a high resistance state (HRS). The dashed lines on the RS represent a setting limit of current flow, i.e., the compliance current $I_{\mathrm{comp}}$.Reuse & Permissions

Figure 2

Temperature ($T$)-dependent changes of RS type in a NiO film. (a), (b), (c), and (d) show the $I\mathrm{\text{−}}V$ curves measured at 118, 300, 80, and 300 K, respectively. Note that memory and threshold RS behaviors are reversible during repeated thermal cycling. The inset in Fig. 2d shows the details on a linear $y$ scale for the resistance changes, marked with the dashed area.Reuse & Permissions

Figure 3

$T$-dependent conductance $G$ values at a bias voltage of 0.2 V for the NiO film. There are bistable states for $T\leqq 156\mathrm{K}$, i.e., the region with memory RS. However, there is only one stable state for $T\geqq 225\mathrm{K}$, i.e., the region with threshold RS.Reuse & Permissions

Figure 4

(a) Schematic diagram of a random circuit breaker (RCB) network composed of circuit breakers. The thick solid (red) and thin dotted (blue) line represent the on and off states, respectively. (b) The switching rules for turning on and off operations in the original RCB network model [15]. Note that both switching rules are governed by electric fields. (c) The newly assigned switching rules in this Letter. The heat $Q$ of each circuit breaker is assumed to be dissipated to a thermal bath of temperature $T_b$. When its local temperature $T_{\mathrm{loc}}$ becomes higher than a threshold temperature $T_c$, it will change its resistance from $r_l$ to $r_h$ (a thermal-driven process). On the other hand, if the applied bias becomes larger than $v_{\mathrm{on}}$, the state with $r_h$ will change to $r_l$, independent of $T_{\mathrm{loc}}$.Reuse & Permissions

Figure 5

Simulation results for $I\mathrm{\text{−}}V$ curves for the cases of $T_b/T_c$ values of (a) 0.3 and (b) 0.75. The former and latter correspond to memory and threshold RS, respectively. The inset in (b) shows the simulation result when $V$ is decreased gradually after reaching the formed state.Reuse & Permissions