Lattice effects on magnetic and transport properties in La 0.67-x Gd x Sr 0.33 CoO 3

The lattice effects on the magnetic and transport properties in La_0.67-xGd_xSr_0.33CoO₃ series are studied. The introduction of smaller Gd³⁺ ions leads to an enhanced mismatch between the La-O layer and the CoO₂ layer and a decrease of the tolerance factor <i>t</i>. The spin-state of trivalent Co ion transits to low-spin state with the decrease of Co-O bond length. The doping of Gd³⁺ drives the system from the cluster-glass state to the spin-glass state and progressively decreases the Curie temperature. At high Gd³⁺ doping content, an interesting negative magnetoresistance occurs at low temperature.

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