Normal-state properties of the antiperovskite oxide Sr${}_{3-x}$SnO revealed by ${}^{119}$Sn-NMR

Abstract

We have performed ${}^{119}$Sn-NMR measurements on the antiperovskite oxide superconductor Sr${}_{3-x}$SnO to 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 Sr${}_{3-x}$SnO phases. The measurement of the nuclear spin-lattice relaxation rate $1/T_1$ 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 $1/T_1$, attributable to the presence of a Dirac-electron band.

5 pages, 4 figures