Optical creation of a supercrystal with three-dimensional nanoscale periodicity
Stoica, V.A., N. Laanait, C. Dai, Z. Hong, Y. Yuan, Z. Zhang, S. Lei, M.R. McCarter, A. Yadav, A.R. Damodaran, S. Das, G.A. Stone, J. Karapetrova, D.A. Walko, X. Zhang, L.W. Martin, Ramamoorthy Ramesh, L.-Q. Chen, H. Wen, V. Gopalan, J.W. Freeland
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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