Hole-Doping Effect on the Spin State and Microscopic Magnetic Properties ofLa1-xSrxCoO3(0≤x≤0.5):59Coand139LaNMR Measurements

Abstract

59 Co and 139 La NMR measurements have been made to reveal microscopically the hole-doping effect on the spin state and magnetic properties of La 1- x Sr x CoO 3 (0≤ x ≤0.5). The signal from the Co atoms with no Sr nearest neighbors was observed in the spin-glass region below x c ∼0.18. From the analysis of the temperature dependence of the Knight shift, the ground state of such Co atoms was found to be the trivalent low-spin state 1 A 1g . Above x c , we observed at 4.2 K the 59 Co and 139 La signals which come from the cluster-glass region with a finite ferromagnetic correlation. Thus, it was microscopically confirmed that the boundary between the two regions is located at x c ∼0.18.