Structure and magnetism in Ho_1-xSr_xCoO _3-δ

We have magnetically and structurally characterized the Ho _1-xSr_xCoO_3-δ family of materials where 0.67 ≤x≤ 0.95. The solid solution range and evolution of the structure as a function of x is established and correlated with the broad range of magnetic behavior observed. The structure is shown to be tetragonal I4/mmm although is possibly cubic Pm3̄m when x=0.95. For 0.67≤x≤0.9 the material shows antiferromagnetic long range order and ferromagnetic clusters. At x=0.95 the magnetic transition is at 120 K and the imaginary susceptibility becomes non-zero and the temperature of the cusp in the ac susceptibility shows a frequency dependence indicative of glassiness.