title: Direct observation of polar tweed in LaAlO3.
abstract: Polar tweed was discovered in mechanically stressed LaAlO3. Local patches of strained material (diameter ca. 5 μm) form interwoven patterns seen in birefringence images, Piezo-Force Microscopy (PFM) and Resonant Piezoelectric Spectroscopy (RPS). PFM and RPS observations prove unequivocally that electrical polarity exists inside the tweed patterns of LaAlO3. The local piezoelectric effect varies greatly within the tweed patterns and reaches magnitudes similar to quartz. The patterns were mapped by the shift of the Eg soft-mode frequency by Raman spectroscopy.
authors.affiliation: Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.|Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.
authors.forename: Ekhard K H
authors.initials: EK
authors.lastname: Salje
authors.affiliation: University of Warwick, Department of Physics, Coventry CV4 7AL, W Midlands, England.
authors.forename: Marin
authors.initials: M
authors.lastname: Alexe
authors.affiliation: Universite des Illes Balears, Department Fisica, E-07122 Palma De Mallorca, Spain.
authors.forename: Sergey
authors.initials: S
authors.lastname: Kustov
authors.affiliation: Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.|Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.
authors.forename: Mads C
authors.initials: MC
authors.lastname: Weber
authors.affiliation: Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.
authors.forename: Jason
authors.initials: J
authors.lastname: Schiemer
authors.affiliation: Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.|Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.|SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France.
authors.forename: Guillaume F
authors.initials: GF
authors.lastname: Nataf
authors.affiliation: Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.|Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg.
authors.forename: Jens
authors.initials: J
authors.lastname: Kreisel