Strain Wave Pathway to Semiconductor-to-Metal Transition revealed by time resolved X-ray powder diffraction

Abstract

Thanks to the remarkable developments of ultrafast science, one of today's challenges is to modify material state by controlling with a light pulse the coherent motions that connect two different phases. Here we show how strain waves, launched by electronic and structural precursor phenomena, determine a macroscopic transformation pathway for the semiconducting-to-metal transition with large volume change in bistable Ti${}_3$O${}_5$ nanocrystals. Femtosecond powder X-ray diffraction allowed us to quantify the structural deformations associated with the photoinduced phase transition on relevant time scales. We monitored the early intra-cell distortions around absorbing metal dimers, but also long range crystalline deformations dynamically governed by acoustic waves launched at the laser-exposed Ti${}_3$O${}_5$ surface. We rationalize these observations with a simplified elastic model, demonstrating that a macroscopic transformation occurs concomitantly with the propagating acoustic wavefront on the picosecond timescale, several decades earlier than the subsequent thermal processes governed by heat diffusion.

arXiv comment30 pages (including supplementary text), 5 main figures, 9 supplementary figures; corrected author list

References in corpus (4)

• Spatially resolved ultrafast magnetic dynamics launched at a complex-oxide hetero-interface
• Non-equilibrium phase precursors to the insulator-metal transition in V2O3
• Dynamic conductivity scaling in photoexcited V2O3 thin films
• Multiple supersonic phase fronts launched at a complex-oxide hetero-interface

Cited by in corpus (5)

• Layer-by-layer phase transformation in Ti${}_3$O${}_5$ revealed by machine learning molecular dynamics simulations
• Hidden States and Dynamics of Fractional Fillings in tMoTe2 Moiré Superlattices
• The Complex Systems and Biomedical Sciences group at the ESRF: current status and new opportunities after Extremely Brilliant Source upgrade
• Lattice dynamics of photoexcited insulators from constrained density-functional perturbation theory
• Rectification from band gap oscillation