Strongly frustrated magnetism and colossal magnetoresistance in polycrystalline La0.47Ce0.20Ca0.33MnO3

G. ALEJANDRO; D. LAMAS; L.B. STEREN; J. E. GAYONE; G. ZAMPIERI; A. CANEIRO; M.T. CAUSA; M. TOVAR

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2003 vol. 67 p. 644241 - 644248

1098-0121

We present x-ray diffraction, x-ray photoemission spectroscopy, magnetization, and transport results on thecerium-doped manganite La0.47Ce0.20Ca0.33MnO3. We have achieved good quality, single-phase polycrystallinesamples by the nitrate decomposition route. A Rietveld analysis of the x-ray spectrum revealed a distortedstructure with a small Mn-O-Mn apical angle of 152.6°. We found that both 31 and 41 charge states ofcerium ions coexist, introducing an additional source of cation disorder in the A site of the perovskite structure.The low-temperature magnetization measurements, together with the high-T susceptibility results, indicate amagnetically frustrated behavior below TF'70 K. The zero-field resistivity shows, at TM'145 K, the typicalmetal-insulator transition found in manganite systems, though a temperature for a long-range ferromagneticorder transition does not obviously exist. The magnetoresistance ~MR! is large, with a maximum value close to100%. Strong hysteresis effects are observed in the MR vs field curves, that correlate well with the magnetizationvs temperature measurements. We discuss these observations and show that the resistivity results areclosely related to the magnetic behavior of the system.