1202.3387 (R. Jarrier et al.)

Surface phase transitions in BiFeO3 below room temperature    [PDF]

R. Jarrier, X. Marti, J. Herrero-Albillos, P. Ferrer, R. Haumont, P. Gemeiner, G. Geneste, P. Berthet, T. Schülli, P. Cvec, R. Blinc, Stanislaus S. Wong, Tae-Jin Park, M. Alexe, M. A. Carpenter, J. F. Scott, G. Catalan, B. Dkhil

We combine a wide variety of experimental techniques to analyze two
heretofore mysterious phase transitions in multiferroic bismuth ferrite at low
temperature. Raman spectroscopy, resonant ultrasound spectroscopy, EPR, X-ray
lattice constant measurements, conductivity and dielectric response, specific
heat and pyroelectric data have been collected for two different types of
samples: single crystals and, in order to maximize surface/volume ratio to
enhance surface phase transition effects, BiFeO3 nanotubes were also studied.
The transition at T=140.3K is shown to be a surface phase transition, with an
associated sharp change in lattice parameter and charge density at the surface.
Meanwhile, the 201K anomaly appears to signal the onset of glassy behaviour.

View original: http://arxiv.org/abs/1202.3387