Evidence for weak antilocalization-weak localization crossover and metal-insulator transition in CaCu$_{3}$Ru$_{4}$O$_{12}$ thin films

TL;DR

This study demonstrates how reducing the thickness of CaCu$_{3}$Ru$_{4}$O$_{12}$ thin films induces a transition from metallic to insulating behavior, with observable weak antilocalization to weak localization crossover driven by quantum interference effects.

Contribution

It provides experimental evidence of dimensionality-induced metal-insulator transition and WAL-WL crossover in CaCu$_{3}$Ru$_{4}$O$_{12}$ thin films, highlighting the role of quantum interference.

Findings

Metal-insulator transition below 3 nm thickness.

Observation of WAL to WL crossover in magnetoconductance.

Strong interplay between inelastic and spin-orbit scattering lengths.

Abstract

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 CaCu$_{3}$Ru$_{4}$O$_{12}$. 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 $h/e^{2} \sim 25~$k$\Omega$, 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.