Strain wave pathway to semiconductor-to-metal transition revealed by time-resolved X-ray powder diffraction.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 33623010.
- Also identified by DOI 10.1038/s41467-021-21316-y and PMC identifier 7902810.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
One of the main challenges in ultrafast material science is to trigger phase transitions with short pulses of light. Here we show how strain waves, launched by electronic and structural precursor phenomena, determine a coherent macroscopic transformation pathway for the semiconducting-to-metal transition in bistable Ti<sub>3</sub>O<sub>5</sub> nanocrystals. Employing femtosecond powder X-ray diffraction, we measure the lattice deformation in the phase transition as a function of time. We monitor the early intra-cell distortion around the light absorbing metal dimer and the long range deformations governed by acoustic waves propagating from the laser-exposed Ti<sub>3</sub>O<sub>5</sub> surface. We developed a simplified elastic model demonstrating that picosecond switching in nanocrystals happens concomitantly with the propagating acoustic wavefront, several decades faster than thermal processes governed by heat diffusion.