Ashok Kumar, J. F. Scott, R. Martinez, G. Srinivasan, R. S. Katiyar
In-plane temperature dependent dielectric behavior of BiFeO3 (BFO) as-grown
thin films show diffuse but prominent phase transitions near 450 (+/-10) K and
550 K with dielectric loss temperature dependences that suggest skin layer
effects. The 450 K anomalies are near the "transition" first reported by
Polomska et al. [Phys. Stat. Sol. 23, 567 (1974)]. The 550 K anomalies coincide
with the surface phase transition recently reported [Xavi et al. PRL 106,
236101 (2011)]. In addition, anomalies are found at low temperatures: After
several experimental cycles the dielectric loss shows a clear relaxor-like
phase transition near what was previously suggested to be a spin reorientation
transition (SRT) temperature (~ 201 K) for frequencies 1 kHz < f < 1MHz which
follow a nonlinear Vogel-Fulcher (V-F) relation; an additional sharp anomaly is
observed near ~180 K at frequencies below 1 kHz. As emphasized recently by
Cowley et al. [Adv. Phys. 60, 229 (2011)], skin effects are expected for all
relaxor ferroelectrics. Using the interdigital electrodes, experimental data
and a theoretical model for in-plane longitudinal and transverse direct
magnetoelectric (ME) coefficient are presented.
View original:
http://arxiv.org/abs/1202.4363
No comments:
Post a Comment