Normal-state properties of the antiperovskite oxide Sr₃₋xSnO revealed by ¹¹⁹Sn-NMR

Abstract

We have performed ¹¹⁹Sn-NMR measurements on the antiperovskite oxide superconductor Sr₃₋xSnOto investigate how its normal state changes with the Sr deficiency. A two-peak structure was observed in the NMR spectra of all the measured samples. This suggests that the phase separation tends to occur between the nearly stoichiometric and heavily Sr-deficient Sr₃₋xSnO phases. The measurement of the nuclear spin-lattice relaxation rate 1/T₁ indicates that the Sr-deficient phase shows a conventional metallic behavior due to the heavy hole doping. In contrast, the nearly stoichiometric phase exhibits unusual temperature dependence of 1/T₁, attributable to the presence of a Dirac-electron band.