μSR experiments on a haldane system (Y1−xCax)2BaNiO5

We report results of muon spin relaxation (μSR) and magnetic susceptibility measurements on the Haldane system (Y1−xCax)2BaNiO5, in which the chain length is controlled by Ca2+ doping. In the nominally pure system, μSR confirms the lack of static magnetic order down to 100 mK. Spin-glass like behavior of the chain-end spins are observed in Ca doped systems (x = 5 and 7.5%), having shorter chain lengths.