Evidence for weak-antilocalization–weak-localization crossover and metal-insulator transition in CaCu<inf>3</inf>Ru<inf>4</inf>O<inf>12</inf> thin films

Artificial confinement of electrons by tailoring the layer thickness has turned out to be a powerful tool to harness control over competing phases in nano-layers of complex oxides. We investigate the effect of dimensionality on transport properties of d-electron–based heavy-fermion metal CaCu3Ru4O12. Transport behavior evolves from metallic to localized regime upon reducing thickness and a metal-insulator transition is observed below 3 nm film thickness for which sheet resistance crosses h/e2 ∼ 25 kΩ, the quantum resistance in 2D. Magnetotransport study reveals a strong interplay between inelastic and spin-orbit scattering lengths upon reducing thickness, which results in weak-antilocalization (WAL) to weak-localization (WL) crossover in magnetoconductance.