Abstract
We have performed -NMR measurements on the antiperovskite oxide superconductor 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 phases. The measurement of the nuclear spin-lattice relaxation rate 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 , attributable to the presence of a Dirac-electron band.
- Received 5 July 2018
- Revised 17 August 2018
DOI:https://doi.org/10.1103/PhysRevB.98.100503
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