LaAlO3: A substrate material with unusual ferroelastic properties

• Published in: Applied physics letters 2018-01, Vol.112 (4)
• Main Authors: Kustov, S., Liubimova, Iu, Salje, E. K. H.
• Format: Article
• Language: English
• Subjects: Amplitudes; Anelasticity; Applied physics; Diffraction; Electric power distribution; Nonlinear dynamics; Phase transitions; Pinning; Power law; Singularities; Strain; Stress concentration; Substrates; Temperature; Twin boundaries
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.5017679

Twin boundary dynamics in LaAlO3 is associated with non-linear anelasticity. Ultrasonic studies of non-linear twin boundary dynamics between 80 and 520 K show that cooling substrates from temperatures near the ferroelastic transition at 813 K generate three characteristic thermal regimes with different non-linear dynamics. Twin boundaries are initially highly mobile. Anelastic strain amplitudes versus stress are power law distributed with an exponent of 2.5. No de-pinning was found down to elastic strain amplitudes of ε0 ∼ 10−7. The power law is gradually replaced between 370 K and 280 K by few large singularities (jerks) due to massive rearrangements of the domain structure for ε0 larger than ca. 5 × 10−5. At lower temperatures, the domain structure is pinned with well-defined thresholds for de-pinning. The de-pinning is not accompanied by global rearrangements of twin patterns below room temperature. Unexpectedly, the low-temperature critical de-pinning strain amplitude decreases with decreasing temperature, which may indicate an additional, so far unknown phase transition near 40 K.