Impurity effect in a novel spin-Peierls compound TiOBr

Abstract We have performed magnetic susceptibility and electron diffraction measurements on impurity effect in a novel spin-Peierls system TiOBr, i.e. Ti 1 - x Sc x OBr . The impurity-induced antiferromagnetic long-range order found in Cu 1 - x Zn x GeO 3 could not be observed in this system. A number of unpaired spins induced by the impurities can be explained by a simple model that one Sc impurity creates one S = 1 2 spin up to the threshold concentration, x c ∼ 0.025 . The induced impurity suppresses the spin-Peierls transition temperature, T c 1 and the spin-Peierls phase disappears at x t ∼ 0.028 , although the incommensurate state still persists above x t . Both values agree well with each other.