Single-crystal growth of spinel type GeNi2O4 and GeCo2O4 by FZ method and their AC susceptibility

Cubic spinel GeNi2O4 and GeCo2O4 compounds exhibit field-induced magnetic anisotropy below the antiferromagnetic transition temperature. GeNi2O4 has two antiferromagnetic like transitions at 12.1 K and 11.4 K. Structural phase transitions (PT) which may lower the symmetry and relief frustration of m...

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Bibliographic Details
Published inJournal of physics. Conference series Vol. 150; no. 4; p. 042213
Main Authors Tominaga, A, Sato, H, Hara, S, Umeyama, N, Ikeda, S I
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.03.2009
Subjects
Antiferromagnetism
Crystal growth
Crystals
Ferromagnetism
High temperature
Induced magnetic anisotropy
Low temperature
Phase transitions
Physics
Single crystals
Spinel
Symmetry
Temperature
Transition temperature
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Summary:Cubic spinel GeNi2O4 and GeCo2O4 compounds exhibit field-induced magnetic anisotropy below the antiferromagnetic transition temperature. GeNi2O4 has two antiferromagnetic like transitions at 12.1 K and 11.4 K. Structural phase transitions (PT) which may lower the symmetry and relief frustration of magnetic spins are expected at the temperatures. However, this cubic material does not undergo a structural PT. On the other hand, GeCo2O4 has a structural PT from high-temperature cubic symmetry to low-temperature tetragonal one at the temperature. Although GeCo2O4 demonstrates antiferromagnetic ordering, derived Weiss temperature is ferromagnetic (11.9 K). In order to understand those intriguing ground states in detail, we have measured AC susceptibility below 1 K. The results show there are no other phase transitions above 150 mK for both compounds.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/150/4/042213