Itinerantf-Electron Antiferromagnetism in NpSn3

Abstract

We report measurements of the specific heat, Mössbauer effect, and electrical resistivity of Np${\mathrm{Sn}}_3$, which identify its weak antiferromagnetism ($T_{\mathrm{N}}=9.5\mathrm{}$ K) as arising from itinerant $5f$ electrons. This is the first known verification of itinerant $f$-electron antiferromagnetism in any system.