Electronic vs. phononic thermal transport in Cr-doped V2O3 thin films across the Mott transition

TL;DR

This study investigates how chromium doping and structural phases affect thermal conductivity in V2O3 thin films across the metal-insulator transition, revealing phonon-dominated heat transport even in metallic phases.

Contribution

It provides detailed measurements of thermal conductivity across doping levels, phases, and temperatures, highlighting the dominant role of lattice vibrations over electrons in heat transport.

Findings

Chromium doping and crystallinity significantly influence thermal conductivity.

Lattice vibrations dominate heat transport even in metallic V2O3.

Both amorphous and crystalline phases show glass-like thermal behavior.

Abstract

Understanding the thermal conductivity of chromium doped V2O3 is crucial for optimizing the design of selectors for memory and neuromorphic devices. We utilized the time-domain thermoreflectance technique to measure the thermal conductivity of chromium doped V2O3 across varying concentrations, spanning the doping induced metal-insulator transition. In addition, different oxygen stoichiometries and film thicknesses were investigated in their crystalline and amorphous phases. Chromium doping concentration (0%-30%) and the degree of crystallinity emerged as the predominant factors influencing the thermal properties, while the effect of oxygen flow (600-1400 ppm) during deposition proved to be negligible. Our observations indicate that even in the metallic phase of V2O3, the lattice contribution is the dominant factor in thermal transport with no observable impact from the electrons on heat transport. Finally, the thermal conductivity of both amorphous and crystalline V2O3 was measured at cryogenic temperatures (80-450 K). Our thermal conductivity measurements as a function of temperature reveal that both phases exhibit behavior similar to amorphous materials, indicating pronounced phonon scattering effects in the crystalline phase of V2O3.