Ga${}^{3+}$-substitution effects in the weak ferromagnetic oxide LaCo${}_{0.8}$Rh${}_{0.2}$O${}_3$

Abstract

Magnetization and x-ray diffraction have been measured on polycrystalline samples of LaCo${}_{0.8-y}$Rh${}_{0.2}$Ga${}_y$O${}_3$ for $0\le y\le 0.15$ in order to understand the spin state of Co${}^{3+}$ through the Ga${}^{3+}$ substitution effect. The ferromagnetic order in LaCo${}_{0.8}$Rh${}_{0.2}$O${}_3$ below 15 K is dramatically suppressed by the Ga${}^{3+}$ substitution, where the ferromagnetic volume fraction is linearly decreased. The normal state susceptibility also systematically decreases with the Ga content, from which we find that one Ga${}^{3+}$ ion reduces 4.6 ${\mu }_{\mathrm{B}}$ per formula unit. We have evaluated how the concentration of the high-spin state Co${}^{3+}$ changes with temperature by using an extended Curie-Weiss law, and have found that the substituted Rh${}^{3+}$ ion stabilizes the high-spin state Co${}^{3+}$ ion down to low temperatures. We find that Ga${}^{3+}$ preferentially replaces the high-spin state Co${}^{3+}$, which makes a remarkable contrast to our previous finding that Rh${}^{3+}$ preferentially replaces the low-spin state Co${}^{3+}$. These results strongly suggest that the magnetically excited state of LaCoO${}_3$ at room temperature is a mixed state of high-spin state Co${}^{3+}$ and low-spin state Co${}^{3+}$.

arXiv comment5 pages, 6 figures

References in corpus (7)

• The spin state transition in LaCoO${}_3$; revising a revision
• Evidence for orbital ordering in LaCoO3
• Pressure-Induced Intermediate-to-Low Spin State Transition in LaCoO3
• Spin-state polaron in lightly hole-doped LaCoO_3
• Stabilization of the high-spin state of Co${}^{3+}$ in LaCo${}_{1-x}$Rh${}_x$O${}_3$
• Magnetic and transport properties of the spin-state disordered oxide La0.8Sr0.2Co_{1-x}Rh_xO_{3-δ}
• Weak Ferromagnetism in LaCo1-xRhxO3: Anomalous Magnetism Emerging between Two Nonmagnetic End Phases

Cited by in corpus (4)

• Spin state of Co${}^{3+}$ in LaCo${}_{1-x}$Rh${}_x$O${}_3$ investigated by structural phenomena
• Unconventional magnetism in the layered oxide LaSrRhO${}_4$
• Prominent electron-hole asymmetry in thermoelectric transport of LaCoO${}_3$
• Symmetry-resolved elastic anomalies in spin-crossover cobaltite LaCoO${}_3$