Magnetic Properties of Electron-Doped LaCoO3

We studied electron-doped \(\text{LaCo}_{1 - y}\text{Te}_{y}^{6 + }\text{O}_{3}\) by magnetization measurements and neutron scattering. The effective Bohr magneton, estimated by Curie–Weiss fitting around room temperature, is independent of y. This suggests that magnetic Co3+(HS), not nonmagnetic Co3+(LS), is mainly replaced by doped magnetic Co2+(HS). At the lowest temperatures, a Brillouin-function-like saturating behavior persists in the magnetization curves even in the high-y samples, and neither a clear magnetic reflection nor magnetic dispersion is observed by neutron scattering. These findings indicate that the magnetic correlation is very weak, in contrast to the well-known hole-doped LaCoO3 accompanied by a drastic transition to a ferromagnetic metal. However, we also found that the low-y samples exhibit nonnegligible enhancement of the saturated magnetization by ∼2μB per a doped electron. All these characteristics are discussed in the light of the activation and inactivation of a spin-state bloc...