1. Spin-Glass Transition and Giant Paramagnetism in Heavily Hole-Doped Bi2Sr2Co2Oy
- Author
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Hsiang-Hsi Kung, Jiunn-Yuan Lin, Fangcheng Chou, Hung Chang Hsu, Wei-Li Lee, Ben-Li Young, and Jian Huang
- Subjects
Paramagnetism ,Spin glass ,Materials science ,Iodometry ,Spins ,Condensed matter physics ,Geometrical frustration ,Vacancy defect ,Transition temperature ,Doping ,General Physics and Astronomy - Abstract
Hole-doped single crystals of misfit-layered cobaltate Bi2−xPbxSr2−zCo2Oy (x = 0–0.61, y = 8.28–8.62, and z = 0.01–0.22) have been successfully grown using the optical floating-zone method. Heavier hole doping has been achieved through both Pb substitution in the Bi site and the more effective Sr vacancy formation. The Co4+ : Co3+ ratio can be raised significantly from its original ∼1 : 1 to 4.5 : 1, as confirmed by iodometric titration. A spin-glass transition temperature of Tg ∼ 70 K is confirmed by ac susceptibility measurement when the Co4+ : Co3+ ratio becomes higher than 2 : 1, presumably owing to the significantly increased probability of triangular geometrical frustration among antiferromagnetically coupled localized Co4+ spins.
- Published
- 2014