Anomalous spin dynamics in charge ordered, "two-electron" doped manganite Ca0.9Ce0.1MnO3 : consequence of a spin-liquid phase?

Abstract

The 'two-electron' doped rare earth manganites Ca_1_-_xCe_xMnO_3 (x = 0.1, 0.2) are probed using resistivity, ac susceptibility and electron paramagnetic resonance (EPR) measurements across their respective charge ordering (CO) temperatures T_C_O = 180 K and 250 K. The EPR 'g' factor and intensity as well as the transport and magnetic behaviors of the two compositions are qualitatively similar and are as expected for CO systems. However, the EPR linewidth, reflective of the spin dynamics, for x = 0.1, shows a strongly anomalous temperature dependence, decreasing with decreasing temperature below T_C_O in contrast with the sample with x = 0.2 and other CO systems. Keeping in view the evidence for magnetic frustration in the system, we propose that the anomalous temperature dependence of the linewidth is the signature of the occurrence of a disorder driven spin liquid phase, present along with charge ordering