Scaled frequency-dependent transport in the mesoscopically phase-separated colossal magnetoresistive manganite La_{0.625-y}Pr_yCa_{0.375}MnO_3

Abstract

We address the issue of massive phase separation (PS) in manganite family of doped Mott insulators through ac conductivity measurements on La${}_{0.625-y}$Pr${}_y$Ca${}_{0.375}$MnO${}_3$ (0.375 $\le$ y $\le$ 0.275), and establish applicability of the scaling theory of percolation in the critical regime of the PS. Measurements of dc resistivity, magnetization (M(T)) and electron diffraction show incomplete growth of a ferromagnetic (FM) metallic component on cooling the high temperature charge ordered (CO) phase well below Curie temperature. The impedance $\mid$Z(T,f)$\mid$ measured over a frequency (f) range of 10 Hz to 10 MHz in the critical regime follows a universal scaling of the form $\approx$ R(T,0)g(f${\xi }^{2+\theta }$) with $\theta$ $\approx$ 0.86 and the normalized correlation length varying from 1 to 4, suggesting anomalous diffusion of holes in percolating FM clusters.

12 pages and 5 figures

Cited by in corpus (1)

• Tunneling Study of the Charge-Ordering Gap on the Surface of La${}_{0.350}$Pr${}_{0.275}$Ca${}_{0.375}$MnO${}_3$ Thin Films