Nat. Mater. 18, 377–383 (2019)

Ultrashort pulses of visible light can convert superlattices of PbTiO3/SrTiO3 into a ‘supercrystal’ state that features ferroelastic, ferroelectric and polar vortex sub-regions that are ordered in three dimensions. The supercrystal phase studied by Vladimir Stoica and co-workers in the US appears to persist indefinitely under ambient conditions (tests indicate that it is stable for at least 1 year), but can be erased by heating above a critical temperature of 470 K. Characterization of the supercrystal phase by X-ray scattering and microscopy shows that the phase possesses a three-dimensional structure with polar, strain and charge-order with a period on the scale of 30 nm. The supercrystal is created by applying sub-picosecond pulses of blue light (shorter than 900 fs at 400 nm wavelength above a critical fluence of ~25 mJ cm–2) onto the superlattice in order to modify elastic and electrostatic interactions.

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