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.
Bibliographical noteFunding Information:
V.A.S., Y.Y., L.W.M., C.D., L.-Q.C., H.W., V.G. and J.W.F. acknowledge support from the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award Number DE-SC-0012375 for the development of the materials and ultrafast experiments. Z.H., S.L. and G.A.S acknowledge support from the National Science Foundation (DMR-1210588) and National Science Foundation Center for Nanoscale Science grant number DMR-1420620. L.-Q. C. also acknowledges support from NSF DMR-1744213. Use of the Advanced Photon Source was supported by the US Department of Energy, Office of Science, under contract no. DE-AC02–06CH11357. PFM data were collected at PSU, University of California, Berkeley, and at the Center for Nanophase Materials Sciences, a DOE Office of Science User Facility at ORNL. N.L. acknowledges support from the Eugene P. Wigner Fellowship at Oak Ridge National Laboratory (ORNL), a US Department of Energy (DOE) facility managed by UT-Battelle, LLC for US DOE Office of Science under contract no. DE-AC05–00OR22725. R.R. and L.W.M. acknowledge funding from the Gordon and Betty Moore Foundation’s EPiQS Initiative, under grant GBMF5307. NL acknowledges use of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory. V.A.S. would like to thank C.M. Schlepütz and J. Hammonds for their development of rsMap3D, valuable discussions with H. Zhou, S Kalinin, Q. Li, Y. Ren, J. Tischler and D.D. Fong, and C.A. Kurtz for technical support.
© 2019, This is a U.S. government work and not under copyright protection in the U.S.; foreign copyright protection may apply.