Millimeter and submillimeter wave ESR measurement of spin ladder system Sr(Cu1−xZnx)2O3

Abstract

Since the discovery of Haldane system many spin gap systems have been found in the low dimensional quantum spin systems. The existence of the spin gap can be explained by the valence bond solid (VBS) picture. Recently, an antiferromagnetic order is observed experimentally in the non-magnetic impurity doped spin Peierls system (Cu1-xZnx)GeO3. It suggests that the non-magnetic impurity breaks the VBS, and the antiferromagnetic moments are induced. Many theoretical models, which explain the appearance of antiferromagnetic moments by non-magnetic impurities, are proposed. Theorists also expect that antiferromagnetic moments can be induced by doping the non-magnetic impurity in S=l/2 2-leg ladder system. Therefore, experimental studies for 2-leg ladder system are desired. SrCu2O3 is one of the model substance of S=l/2 2-leg ladder system. The crystal structure is described in reference. From the magnetic susceptibility measurements and the neutron measurements of 2-leg ladder system SrCu2O3, the spin gap between the singlet ground state and the first excited state was estimated to be 550K.