Electron weak localization and electron–electron interaction effects on magneto-conductivity in In–Ga–Zn oxide films

• We report detailed analyses of conductance, ∆σ, for three-dimensional In–Ga–Zn oxide films.
• Investigation of ∆σ in wide magnetic field and temperature regions
• Spin–orbit scattering changes with increasing resistivity from light oxygen atoms to heavy atoms.

We investigated the magnetoconductivity ∆σ(H,T) defined by a function of magnetic field H and temperature T for three-dimensional indium–gallium–zinc oxide films in the resistivity ρ range of 0.076 × 10− 3 Ω m ≤ ρ(2.0 K) ≤ 0.55 × 10− 3 Ω m. Here, ∆σ(H,T) is the ∆σ(H,T) ≡ 1 / ρ(H,T) − 1 / ρ(0,T). With increasing ρ, the contribution ∆σEEI due to the electron–electron interaction (EEI) effect overcomes the contribution ∆σWL due to the weak localization (WL) effect. The sign of ∆σ(H) = ∆σEEI + ∆WL changes from positive to negative with increasing magnetic field, particularly at low temperatures. To perform a systematic investigation of ∆σEEI, we obtained the contribution of ∆σEEI using the relation ∆σEEI(H,T) = ∆σexp.(H,T) − ∆σWLtheo.(H,T), where ∆σWLtheo.(H,T  ) is estimated by fitting the WL theory to data at low magnetic fields. It was found that i) ΔσEEIHT/T as a function of H/T for each film collapses onto a single universal curve at a magnetic field of up to 5 T and in the temperature range between 2.0 and 50 K. ii) From the analyses of ΔσEEIHT/T in the high and low H/T regions with the EEI theory, the screening factors F∆σ,H and F∆σ,L were estimated, respectively. iii) The F∆σ,H values satisfy the theoretical prediction as 0 < F < 1. iv) With increasing ρ, the magnitudes of both F∆σ,H and F∆σ,L essentially decrease to approach 0 at ρc ≈ 1.3 × 10− 3 Ω m, where the metal–insulator transition is suggested to occur.