Random interactions and spin-glass thermodynamic transition in the hole-doped Haldane system Y2-xCaxBaNiO5 - art. no. 212406

Magnetization, de and ac bulk susceptibility of the S=1 Haldane chain syste m doped with electronic holes, Y2-xCaxBaNiO5 (O less than or equal tox less than or equal to0.20), have been measured and analyzed. The most striking results are (i) a sub-Curie power law behavior of the linear susceptibility chi (T)similar toT(-alpha), for temperature lower than the Haldane gap of the undoped compound (x=0) and (ii) the existence of a spin-glass thermodyn amic transition at T-g=2-3 K. These findings are consistent with (i) random couplings within the chains between the spin degrees of freedom induced by hole doping and (ii) the existence of ferromagnetic bonds that induce magn etic frustration when interchain interactions come into play at low tempera ture.