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Substitution effect of Zn or Ni atoms for Cu atoms on the magnetic susceptibility and the electronic specific heat Cel have been investigated in La1.875Ba0.125CuO4 where stripe order is formed. The effective magnetic moment, which is evaluated by analyzing the temperature dependence of χ, decreases with increasing Zn substitution but increases with Ni substitution, suggesting that spin substitution from S=1/2 to S=0 or S=1 in spin stripes is brought about by Zn or Ni substitution in the Cu site. The substitution dependence of the electronic specific heat coefficient γ, which is obtained from Cel, differs between Zn and Ni atoms and reveals the full destruction of stripe order by Zn (S=0) and the formation of a new phase by Ni (S=1). The different behaviors can be explained by differences in the spin interaction between the substituted atom and the nearest neighbor Cu atoms, indicating that spin interactions not only create antiferromagnetic order in spin stripes, but also play an important role in the formation of charge stripes. |
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