Berlin 2024 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 11: Focus Session: (Multi-)Ferroic States II

KFM 11.5: Hauptvortrag

Dienstag, 19. März 2024, 11:10–11:40, EMH 225

Optical Formation and Manipulation of Topological Polar Supertextures — •John Freeland — X-ray Science Division, Argonne National Laboratory, Lemont, IL USA

Ultrafast stimuli can stabilize and control metastable states of matter inaccessible by equilibrium means. Establishing the spatiotemporal link between ultrafast excitation and metastability is crucial to understanding these phenomena. This talk will focus on superlattices of PbTiO3 (PTO) and SrTiO3 (STO) that host a variety of extended polar textures such as supercrystals, vortices, skyrmions, collectively dubbed polar supertextures. In particular we will explore the formation of polar supercrystals[1], which is a highly order phase created via optical excitation of these PTO/STO heterostructures. Since the transition is irreversible, an understanding of the formation pathway, we needed to use the high intensity ultrafast X-ray pulses from a free electron laser to track the single-shot dynamics of polar supercrystal creation from ps to us timescales. Together with dynamical phase field modeling, these results enabled tracking of the irreversible formation of this metastable polar supertexture and understanding of the creation process.

The work at Argonne is supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The development of the materials and ultrafast experiments is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DE-SC-0012375.

[1] Stoica, V. A. et al. Nat. Mater. 18, 377 (2019).

Keywords: X-ray diffraction; ultrafast; ferroelectrics; heterostructures; titanates