Anomalous spin dynamics in the charge-ordered two-electron doped manganite Ca_0.9Ce_0.1MnO₃: Possibility of a spin-liquid phase

Abstract

The “two-electron" doped rare earth manganites Ca_1-xCe_xMnO₃ (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_CO=180 and 250 K. The EPR resonance field 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_CO 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.