Novel Transitions in Doped Mott-Insulator Kx CoO2
YANG Hai-Peng, LU Xi-Feng, WEN Hai-Hu
National Laboratory for Superconductivity, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080
Novel Transitions in Doped Mott-Insulator Kx CoO2
YANG Hai-Peng;LU Xi-Feng; WEN Hai-Hu
National Laboratory for Superconductivity, Institute of Physics and Center for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100080
关键词 ：
74.10.+v ,
74.20.Mn ,
75.47.Pq ,
74.25.Gz
Abstract ： By measuring the temperature dependence of the magnetic susceptibility, two distinct transitions have been observed in potassium doped cobalt oxide Kx CoO2 (x = 0.2-1.0). The transition around 125 K corresponds to a phase transition between a weak ferromagnetic plus a strong superparamagnetic phase (below 125 K) and a superparamagnetic phase (above 125 K). The susceptibility above the Curie point Tc cannot be described by the Curie-Weise law, being consistent with the superparamagnetism. Magnetization-hysteresis-loops have been measured in different temperature regions to uncover the underlying physics. The second transition near 30.8 K shows a strong novelty.
Key words ：
74.10.+v
74.20.Mn
75.47.Pq
74.25.Gz
出版日期: 2003-05-01
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2003, Vol. 20 
