EVIDENCE OF A SPIN-PEIERLS DISTORTION IN THE QUASI-ONE-DIMENSIONAL MAGNETIC COMPOUND CUGEO3

Neutron diffraction experiments were carried out on an inorganic quasi-one-dimensional magnet with spin 1/2, CuGeO3, and showed satellite peaks arising due to the dimerization of Cu atoms. Displaying a spin-Peierls transition, Cu ions with spin 1/2 were found to reach a singlet ground state having alternating displacements between Cu atoms. Taking the shift of a Cu atom as an order parameter, the critical exponent beta becomes 0.5 and the shift resulting from dimerization along the c axis is about 1% of the lattice constant c at 2.7 K.