Mott transition in Cr-doped V2O3 studied by ultrafast reflectivity: electron correlation effects on the transient response

TL;DR

This study uses ultrafast pump-probe reflectivity to investigate how electron correlations influence the transient response during the metal-insulator transition in Cr-doped V2O3, revealing the roles of coherent phonons and electronic effects.

Contribution

It provides a detailed analysis of the ultrafast dynamics across the phase diagram, highlighting the importance of lattice and electronic interplay in the Mott transition.

Findings

Coherent acoustic waves vary with phase and electron density of states.

Lattice oscillations significantly affect ultrafast electronic relaxation.

Understanding ultrafast response requires considering both electronic and lattice effects.

Abstract

The ultrafast response of the prototype Mott-Hubbard system (V1-xCrx)2O3 was systematically studied with fs pump-probe reflectivity, allowing us to clearly identify the effects of the metal-insulator transition on the transient response. The isostructural nature of the phase transition in this material made it possible to follow across the phase diagram the behaviour of the detected coherent acoustic wave, whose average value and lifetime depend on the thermodynamic phase and on the correlated electron density of states. It is also shown how coherent lattice oscillations can play an important role in some changes affecting the ultrafast electronic peak relaxation at the phase transition, changes which should not be mistakenly attributed to genuine electronic effects. These results clearly show that a thorough understanding of the ultrafast response of the material over several tenths of ps is necessary to correctly interpret its sub-ps excitation and relaxation regime, and appear to be of general interest also for other strongly correlated materials.