TY - JOUR
T1 - Melting of antiferromagnetic ordering in spinel oxide CoAl 2O4
AU - Suzuki, T.
AU - Nagai, H.
AU - Nohara, M.
AU - Takagi, H.
PY - 2007/4/11
Y1 - 2007/4/11
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=33947678786&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33947678786&partnerID=8YFLogxK
U2 - 10.1088/0953-8984/19/14/145265
DO - 10.1088/0953-8984/19/14/145265
M3 - Article
AN - SCOPUS:33947678786
VL - 19
JO - Journal of Physics Condensed Matter
JF - Journal of Physics Condensed Matter
SN - 0953-8984
IS - 14
M1 - 145265
ER -