Multiple phase transitions in single-crystalline Na$_{1-\delta}$FeAs

TL;DR

This study investigates the multiple phase transitions in high-quality Na$_{1-\

Contribution

It provides direct experimental evidence of magnetic ordering and phase transitions in Na$_{1-\

Findings

Three successive phase transitions at 52, 41, and 23 K

Development of an energy gap due to spin-density-wave instability

Confirmation of magnetic ordering in nearly stoichiometric NaFeAs

Abstract

Specific heat, resistivity, susceptibility and Hall coefficient measurements were performed on high-quality single crystalline Na$_{1-\delta}$FeAs. This compound is found to undergo three successive phase transitions at around 52, 41, and 23 K, which correspond to structural, magnetic and superconducting transitions, respectively. The Hall effect result indicates the development of energy gap at low temperature due to the occurrence of spin-density-wave instability. Our results provide direct experimental evidence of the magnetic ordering in the nearly stoichiometric NaFeAs.