6.3 Summary

We have presented with $\mu$SR that the Zn/Si-doped CuGeO₃ exhibits static order. In the Si-doped Cu(Ge_1-ySi_y)O₃ crystal (y=2%), Néel order was clearly observed with spontaneous muon spin precession. The critical exponent ($\beta$) of the order parameter was found to be the same with the previously-reported value for a Zn-doped crystal, suggesting a universal ordering mechanism between the Si and Zn doping.

In the $\mu$SR measurements of the Zn-doped polycrystalline pellets, Néel order was not clear, probably due to a macroscopic sample inhomogeneity. From the static muon spin relaxation rate, the size of the ordered moments were proposed to mimic the Zn concentration dependence of the Néel temperatures.