Electric-field-induced soft-mode hardening in SrTiO3 films
We have studied electric-field-induced Raman scattering in SrTiO3 thin films using an indium-tin-oxide/SrTiO3/SrRuO3 structure grown by pulsed laser deposition. The soft mode polarized along the field becomes Raman active. Experimental data for electric-field-induced hardening of the soft modes and the tuning of the static dielectric constant are in agreement described by the Lyddane-Sachs-Teller formalism. The markedly different behavior of the soft modes in thin films from that in the bulk is explained by the existence of local polar regions.
Akimov
IA
Department of Physics, the Pennsylvania State University, University Park, Pennsylvania 16802, USA.
Sirenko
AA
Clark
AM
Hao
J
Xi
XX