First-principles study of electronic transport properties of Ta$_2$O$_5$ atomic switch

The atomic switch using solid electrolyte such as Ta$_2$O$_5$ has attracted attention as a promising novel nanoscale device. In the case of the Ta$_2$O$_5$ switch, experiments shows that the precipitation of metal in the Ta$_2$O$_5$ layer plays a crucial role in forming the low resistance state of the switch. However, atomistic details of the conduction path have not been clarified yet. In this work, we have examined the electronic transport properties of the low resistance state of the Cu/Ta$_2$O$_5$/Pt atomic switch using the density functional theory (VASP code) and non-equilibrium Green's function method (ATK code). Our results show that a Cu chain bridging Cu and Pt electrodes works as a conduction path in the case of crystalline Ta$_2$O$_5$. On the other hand, preliminary results show that the conduction through similar Cu chain structures is unexpectedly low in the case of amorphous Ta$_2$O$_5$.