Melting of antiferromagnetic ordering in spinel oxide CoAl 2O4

T. Suzuki, H. Nagai, M. Nohara, H. Takagi

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Abstract

The magnetic and thermal properties of the spinel oxides CoB 2O4 have been studied for B ≤ Rh, Co and Al. The compounds consist of magnetic Co2+ (S ≤ 3/2) in the A site and non-magnetic B3+ in the B site, which form diamond and pyrochlore sublattices, respectively. We found that the ratio of the Curie-Weiss temperature to the magnetic ordering temperature, |ΘCW|/T N, depends strongly on B3+ cations. CoRh2O 4 was a typical antiferromagnet with |ΘCW|/T N ≤ 31 K/25 K ≤ 1.2. The ratio was enhanced up to |ΘCW|/TN ≤ 110 K/30 K ≤ 3.7 for Co 3O4 (B ≤ Co) and |ΘCW|/T * ≤ 89 K/9 K ≤ 10 for CoAl2O4, indicating the evolution of magnetic frustration. The specific heat for CoAl2O4 exhibited a broad peak at T* ≤ 9 K and T2.5 behaviour at low temperatures, suggesting the most frustrated magnet CoAl2O4 is in the critical vicinity of a quantum melting point of the antiferromagnetically ordered state.

Original languageEnglish
Article number145265
JournalJournal of Physics Condensed Matter
Volume19
Issue number14
DOIs
Publication statusPublished - Apr 11 2007
Externally publishedYes

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ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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