Hole-induced Novel Spin State within Haldane Gap in Nd2-xCaxBaNiO5

Static and dynamical spin properties in a hole-doped one-dimensional Haldane chain system have been investigated by magnetization and neutron scattering measurements on antiferromagnetic Nd 2- x Ca x BaNiO 5 . Spin-glass-like weak ferromagnetic behavior and an incommensurate dynamical structure were observed, which are similar to those reported in the Haldane system Y 2- x Ca x BaNiO 5 . A novel excitation, moreover, has been revealed at 10 meV because of complete the shift in the Haldane gap due to three-dimensional antiferromagnetic ordering, which possibly provides a total picture of a hole-induced quantum Haldane chain.