We report the bulk magnetic properties of hole-doped ${\mathrm{La}}_{1-x}{\mathrm{Ca}}_x{\mathrm{MnO}}_3$ $(0⩽x⩽0.14)$ in the paramagnetic and antiferromagnetic regions; the ${\mathrm{Mn}}^{4+}$ concentration was determined with chemical analysis. Significant enhancement of the effective paramagnetic moment illustrates the existence of ferromagnetic clusters (polarons). The data reveal a distinct crossover in the paramagnetic region, signifying competition between ferromagnetic clusters and antiferromagnetic correlations associated with the low-temperature magnetically ordered state. The results suggest similarity in the magnetic properties at low temperatures between hole-doped ${\mathrm{LaMnO}}_3$ and electron-doped ${\mathrm{CaMnO}}_3$.

• Received 18 July 2003

DOI:https://doi.org/10.1103/PhysRevB.71.134402