Dimerization ofCuGeO3in the Spin-Peierls State

Abstract

The dimerization of the Cu ions in the spin-Peierls state of ${\mathrm{CuGeO}}_3$ below 14 K has been determined by neutron-diffraction measurements. In addition to superlattice reflections with indices $\frac{h}{\frac{2kl}{2}}$ ($h$, $k$, $l$, all odd) recently observed in electron and x-ray diffraction studies, we also found peaks for which $k=5\mathrm{}$ = even. Oxygen displacements in the $a-b$ plane of about 0.01 Å, accompanied by comparable shifts of the Cu ions along the chain direction $c$, can be related to the dimerized spin state in a natural fashion.