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

TL;DR

This study uses $^{119}$Sn-NMR to explore how Sr deficiency affects the normal-state electronic properties of Sr$_{3-x}$SnO, revealing phase separation and contrasting metallic and Dirac-electron behaviors.

Contribution

It provides new insights into the phase separation and electronic states in Sr$_{3-x}$SnO using NMR, highlighting the effects of Sr deficiency on its normal state.

Findings

Phase separation between nearly stoichiometric and Sr-deficient phases.

Sr-deficient phase shows conventional metallic behavior.

Nearly stoichiometric phase exhibits unusual temperature dependence due to Dirac electrons.

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.