Structural Evidence for a Spin Peierls Ground state in the Quasi-One-Dimensional Compound CuGeO3

Abstract

X-ray and elastic neutron scattering measurements reveal that the quasi-one-dimensional ${\mathrm{Cu}}^{2+}(S=\frac{1}{2})$ antiferromagnet CuGe${\mathrm{O}}_3$ undergoes a second order structural transition towards a dimerized ground state at the same temperature, $T_{\mathrm{SP}}=14\mathrm{}$ K, at which the magnetic susceptibility abruptly decreases. X-ray diffuse scattering measurements show that the critical fluctuations are quasi one dimensional on a large temperature range above $T_{\mathrm{SP}}$. These results show unambiguously that CuGe${\mathrm{O}}_3$ undergoes a true spin-Peierls transition triggered by the magnetic chains.