Heat capacity studies of magnetic phase transition in sodium-rich NaxCoO₂ (0.73 ≤ x ≤ 0.87)

Heat capacity studies of magnetic phase transition in sodium-rich NaxCoO₂ (0.73 ≤ x ≤ 0.87)

Baran, A. ; Botko, M. ; Zorkovská, A. ; Kajňaková, M. ; Šebek, J. ; Šantavá, E. ; Peng, J.P. ; Lin, C.T. ; Feher, A.

Тема: Низкотемпеpатуpный магнетизм

Інший ID: PACS: 75.30.Kz, 71.27.+a, 75.40.Cx

URI: http://dspace.nbuv.gov.ua/handle/123456789/117413

Посилання: Heat capacity studies of magnetic phase transition in sodium-rich NaxCoO₂ (0.73 ≤ x ≤ 0.87) / A. Baran, M. Botko, A. Zorkovská, M. Kajňaková, J.Šebek, E. Šantavá, J.P. Peng, C.T. Lin, A. Feher // Физика низких температур. — 2009. — Т. 35, № 10. — С. 1030-1033. — Бібліогр.: 29 назв. — англ.

Підтримка: This work was supported by the grants of Slovak Research and Development Agency under the contracts No. APVV-VVCE-0058-07 and No. APVV-0006-07, VEGA 1/0159/9, the NSF-0701400 project and the Slovak–Serbian bilateral project SK-SRB-01006 and AVOZ 10100520.

Дата: 2009

Завантажень: 655

Heat capacity studies of magnetic phase transition in sodium-rich NaxCoO₂ (0.73 ≤ x ≤ 0.87)

Анотація:

Specific heat measurements in the temperature region from 2 to 50 K in magnetic field up to 10 T, oriented parallel and perpendicularly to the CoO₂ layers were carried out on a series of high-quality single- crystals of NaxCoO₂ (x = 0.73, 0.76, 0.77, 0.78 and 0.87). Surprisingly, sharp lambda type anomaly was observed only for the concentration x = 0.76 at temperature (21.80 ± 0.02) K, for all the remaining doping levels round anomaly in experimental data was visible at temperature ~ 20 K, indicating a smeared magnetic phase transition. While the magnetic field oriented perpendicularly to the CoO₂ layers shifts the temperature of this anomaly to lower values, parallel magnetic field has no influence on it, what indirectly supports the idea of A-type antiferromagnetic ordering in studied systems.

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