Non-thermal fluence threshold for femtosecond pulsed x-ray radiation damage in perovskite complex oxide epitaxial heterostructures

Abstract

Intense hard x-ray pulses from a free-electron laser induce irreversible structural damage in a perovskite oxide epitaxial heterostructure when pulse fluences exceed a threshold value. The intensity of x-ray diffraction from a 25-nm thick epitaxial BiFeO${}_3$ layer on a SrTiO${}_3$ substrate measured using a series of pulses decreases abruptly with a per-pulse fluence of 2.7 x 10${}^6$ photons $\mu$m${}^{-2}$ at 9.7 keV photon energy, but remains constant for 1.3 x 10${}^6$ photons $\mu$m${}^{-2}$ or less. The damage resulted in the destruction of the BiFeO${}_3$ thin film within the focal spot area and the formation of a deep cavity penetrating into the STO substrate via the removal of tens of nanometers of material per pulse. The damage threshold occurs at a fluence that is insufficient to heat the absorption volume to the melting point. The morphology of the ablated sample is consistent with fracture rather than melting. Together these results indicate that the damage occurs via a non-thermal process consistent with ultrafast ionization of the absorption volume.

arXiv commentThe following article has been accepted by Applied Physics Letters

References in corpus (5)

• The beta Phase of Multiferroic Bismuth Ferrite and its beta-gamma Metal-Insulator Transition
• Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO${}_3$
• Statistical and coherence properties of radiation from X-ray free electron lasers
• Various damage mechanisms in carbon and silicon materials under femtosecond x-ray irradiation
• Domain alignment within ferroelectric/dielectric PbTiO${}_3$/SrTiO${}_3$ superlattice nanostructures

Cited by in corpus (1)

• Optically Induced Picosecond Lattice Compression in the Dielectric Component of a Strongly Coupled Ferroelectric/Dielectric Superlattice