Ga3+ substitution effects in the weak ferromagnetic oxide LaCo0.8Rh0.2O3

Article

关键词: SPIN-STATE TRANSITION;    LACOO3;   

DOI  :  10.1103/PhysRevB.86.014421

来源: SCIE

【 摘 要 】

Magnetization and x-ray diffraction have been measured on polycrystalline samples of LaCo0.8-yRh0.2GayO3 for 0 <= y <= 0.15 in order to understand the spin state of Co3+ through the Ga3+ substitution effect. The ferromagnetic order in LaCo0.8Rh0.2O3 below 15 K is dramatically suppressed by the Ga3+ substitution as the ferromagnetic volume fraction is linearly decreased. The normal state susceptibility also systematically decreases with the Ga content from which we find that one Ga3+ ion reduces 4.6 mu(B) per formula unit. We have evaluated how the concentration of the high-spin-state Co3+ changes with temperature by using an extended Curie-Weiss law and have found that the substituted Rh3+ ion stabilizes the high-spin-state Co3+ ion down to low temperatures. We find that Ga3+ preferentially replaces the high-spin-state Co3+, making a remarkable contrast to our previous finding that Rh3+ preferentially replaces the low-spin-state Co3+. These results strongly suggest that the magnetically excited state of LaCoO3 at room temperature is a mixed state of the high-spin-state Co3+ and the low-spin-state Co3+.

【 授权许可】

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