Effects of V and Gd doping on novel positive colossal electroresistance and quantum transport in PbPdO 2 thin films with (002) preferred orientation.

In this work, PbPd 0.9 V 0.1 O 2 and PbPd 0.9 Gd 0.1 O 2 thin films with (002) preferred orientation were prepared using a pulsed laser deposition technique. The temperature dependence of resistivities ρ I ( T ) was investigated under various applied DC currents. Colossal electroresistance (CER) effects were found in PbPd 0.9 V 0.1 O 2 and PbPd 0.9 Gd 0.1 O 2 . It was found that the positive CER values of PbPd 0.9 V 0.1 O 2 and PbPd 0.9 Gd 0.1 O 2 reach 3816% and 154% for I = 1.00 μA at 10 K, respectively. In addition, the ρ I ( T ) cycle curves of PbPd 0.9 V 0.1 O 2 and PbPd 0.9 Gd 0.1 O 2 thin films showed a critical temperature similar to that of PbPdO 2 ( T c = 260 K). Particularly, charge transfer between O 1- and O 2- was confirmed by in situ XPS. Additionally, based on first-principles calculations and internal electric field models, the CER and magnetic sources in PbPd 0.9 V 0.1 O 2 and PbPd 0.9 Gd 0.1 O 2 can be well explained. Finally, it was found that thin film samples doped with V and G ions exhibit weak localization (WL) and weak anti-localization (WAL) quantum transport properties. Ion doping leads to a transition from WAL to WL. The study results indicate that PbPdO 2 , one of the few oxide topological insulators, can exhibit novel quantum transport behavior after ion doping.