Effect of spin substitution on stripe order inLa1.875Ba0.125Cu1−yMyO4(M=ZnorNi)

Abstract

The destruction of stripe order by Zn $(S=0)$ and the formation of a new phase by Ni $(S=1)$ are demonstrated directly from the substitution dependence of the electronic coefficient of specific heat $\ensuremath{\gamma}$ in ${\mathrm{La}}_{1.875}{\mathrm{Ba}}_{0.125}{\mathrm{Cu}}_{1\ensuremath{-}y}{M}_{y}{\mathrm{O}}_{4}$ $(M=\mathrm{Zn}$ or Ni). In the Zn-substitution case, \ensuremath{\gamma}, which is strongly suppressed by stripe phase formation, increases to a value that corresponds to the state where there is no stripe order. In the Ni-substitution case, \ensuremath{\gamma} saturates at nearly half the value of the Zn-substitution case. The difference can be explained by a difference in the spin interactions between the substituent atom and the nearest neighbor Cu atoms, indicating that spin interaction plays an important role in the formation of charge stripes.