Publication Type:Journal Article
Source:Nature Materials, Nature Publishing Group, Volume 18, Number 4, p.377-383 (2019)
Keywords:Coherent scattering, Dielectric properties, Lead titanate, light, Magnetic phenomena, Nano-scale periodicity, Non-equilibrium phasis, Phase field models, Photo-induced charge, Three-dimensional structure, Two phase flow, Two-phase equilibria, Ultrafast light pulse, X ray scattering
Stimulation with ultrafast light pulses can realize and manipulate states of matter with emergent structural, electronic and magnetic phenomena. However, these non-equilibrium phases are often transient and the challenge is to stabilize them as persistent states. Here, we show that atomic-scale PbTiO 3 /SrTiO 3 superlattices, counterpoising strain and polarization states in alternate layers, are converted by sub-picosecond optical pulses to a supercrystal phase. This phase persists indefinitely under ambient conditions, has not been created via equilibrium routes, and can be erased by heating. X-ray scattering and microscopy show this unusual phase consists of a coherent three-dimensional structure with polar, strain and charge-ordering periodicities of up to 30 nm. By adjusting only dielectric properties, the phase-field model describes this emergent phase as a photo-induced charge-stabilized supercrystal formed from a two-phase equilibrium state. Our results demonstrate opportunities for light-activated pathways to thermally inaccessible and emergent metastable states. © 2019, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.
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