Dielectric behavior associated to nano-scale electronic phase separation in La0.5Ca0.5MnO3

PABLO M. BOTTA; JOSÉ RIVAS

Barcelona, España

Workshop; 2nd Nanospain Workshop; 2005

The development of materials with high dielectric permittivity is nowadays one of the most important challenges of new technologies. Although standard ferroelectrics are the current solution, there are application fields where these materials exhibit some limitations. One possible alternative is given by materials with condensation of electronic charge. In this way, we have focused on systems with charge condensation, such as charge-ordered manganites. The La0.5Ca0.5MnO3 compound has antiferromagnetic (AF) state with charge ordering (CO); upon heating,  a first  order phase transition to a ferromagnetic (FM) state is observed. Thermal energy inhibits charge localization and AF coupling, and thus the double exchange mechanism leads to a FM state. The competition between FM and CO states gives rise to a electronic phase separation into nano-scale regions of FM and CO below 150 K. In this context, the objective of this work is to contribute to  understand the role of these clusters on the dielectric behavior of La0.5Ca0.5MnO3, focusing on the apparent link between the electronic state and its dielectric response.