Absence of superconductivity in electron-doped chromium pnictides ThCrAsN1-xOx

Theoretical studies predicted possible superconductivity in electron-doped chromium pnictides isostructural to their iron counterparts. Here, we report the synthesis and characterization of a ZrCuSiAs-type Cr-based compound ThCrAsN, as well as its oxygen-doped variants. All samples of ThCrAsN1-xOx show metallic conduction, but no superconductivity is observed above 30 mK even though the oxygen substitution reaches 75%. The magnetic structure of ThCrAsN is determined to be G-type antiferromagnetic by magnetization measurements and first-principles calculations jointly. The calculations also indicate that the in-plane Cr-Cr direct interaction of ThCrAsN is robust against the heavy electron doping. The calculated density of states of the orbital occupations of Cr for ThCrAs(N,O) is strongly spin polarized. Our results suggest the similarities between chromium pnictides and iron-based superconductors should not be overestimated.