Transport study of percolation modes in the mixed-phase manganites

Abstract

Based on the phase separation scenario, cluster percolation mode is introduced to simulate the percolative conduction of ${\mathrm{La}}_{0.9}{\mathrm{Te}}_{0.1}\mathrm{Mn}{\mathrm{O}}_{3}$ and ${\mathrm{La}}_{2∕3}{\mathrm{Ca}}_{1∕3}\mathrm{Mn}{\mathrm{O}}_{3}$ thin films with the abrupt metal-to-insulator transition of resistivity, while standard percolation mode, which seems to work well for ${\mathrm{La}}_{0.9}{\mathrm{Te}}_{0.1}\mathrm{Mn}{\mathrm{O}}_{3}$ bulk with smooth transition, fails in it. The agreement between the simulation and the experimental data reveals that the sizes of the paramagnetic domains in the films increases, but the number of those domains does not change with the increased temperature. This process is very different from the case in the bulk, where the domain sizes almost remain unchanged and the domain number increases with the increased temperature. The present results also further verify that phase separation plays a crucial role in the transport process and the size of coexisting phase may be related to the size of the crystal grains.