High‐pressure synthesis, crystal structure, and magnetic property of LaCo 6 O 11

• Published in: International journal of ceramic engineering & science Vol. 4; no. 2; pp. 123 - 129
• Main Authors: Toda, Fumito, Yamada, Ikuya, Kawaguchi, Shogo
• Format: Journal Article
• Language: English
• Published: 01-03-2022
• ISSN: 2578-3270; 2578-3270
• DOI: 10.1002/ces2.10124

Abstract
A novel cobalt oxide LaCo
6
O
11
has been synthesized under high pressure of 8 GPa, and its crystal structure and magnetic property have been investigated. Rietveld analysis using synchrotron X‐ray powder diffraction data demonstrates that LaCo
6
O
11
crystallizes in the magnetoplumbite‐derived structure as well as
A
2+
Co
6
O
11
(
A
 = Ca, Sr, Ba). Bond valence sum (BVS) calculation exhibits a substantial decrease in BVS of octahedral Co sites with itinerant electrons, whereas BVS at trigonal bipyramidal Co site with localized electrons is unchanged, indicating that the doped electrons are predominantly injected into the Co sites with electric conductivity. Magnetization measurement shows that the magnetic ground state of LaCo
6
O
11
is similar to the antiferromagnetic‐like one in CaCo
6
O
11
. However, the absence of a field‐induced ferrimagnetic transition in LaCo
6
O
11
indicates the robustness of the antiferromagnetic‐like ground state. The difference in the magnetic state under the external magnetic field between LaCo
6
O
11
and CaCo
6
O
11
is attributed to the suppression of the ferromagnetic RKKY interaction because of the reduction in hole carrier density by La
3+
substitution for Ca
2+
.