Abstract
The susceptibility of CuO1-δ and Cu0.99Li0.01O single and polycrystals has been investigated in the temperature range 56–600 K in magnetic fields of up to 13 kOe. It is shown that defects produce a strong effect on the magnitude and behaviour of X(T). Anisotropy of susceptibility in CuO single crystals both below and above TN has been revealed. The analysis of susceptibility has shown that in the T<230 K region CuO is a 3D collinear antiferromagnet with spin S=12 directed along the b axis. A small X minimum was observed for the direction H⊥b in the vicinity of T=212 K. The anomalous behaviour of susceptibility above TN is explained by the quasi-1D magnetic structure comprising Cu-O-Cu antiferromagnetic chains oriented along [101]. The dependence X(T) for a polycrystal is well described by the Heisenberg antiferromagnetic chain model with S=12, Ik=430 K and g=1.97. It has been found not possible to describe the dependences X∥(T) and X⊥(T) in single crystals by means of Heisenberg and Ising models: this may be due to both g-factor and Ik anisotropies.
Published Version
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