Browsing by Author "Huang, Jian"

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Spin-Glass Transition and Giant Paramagnetism in Heavily Hole-Doped Bi2Sr2Co2Oy
(2014-02-01)
Hsu, Hung Chang
;
Lee, Wei-Li
;
Lin, Jiunn-Yuan
;
Young, Ben-Li
;
Kung, Hsiang-Hsi
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 similar to 1 : 1 to 4.5 : 1, as confirmed by iodometric titration. A spin-glass transition temperature of T-g similar to 70K 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.