Synthesis and characterisation of a quaternary nitride series with spin-glass behaviour: SnxGe1−xFe3N

Abstract

We present the chemical synthesis, crystal-structure determination, and magnetic properties of the quaternary iron nitrides Sn_xGe_1−xFe₃N (0 < x < 1). The ternary end members of this series differ in structure, composition, and stability, but both belong to the first spin glasses of iron nitrides. To explore the properties of the quaternary series, a previously established two-step ammonolytic reaction was used to synthesise the compounds. The entire Sn_xGe_1−xFe₃N series adopts the antiperovskite structure in space group Pmm with a fully occupied nitrogen position and a Vegard-type increase of the lattice parameter over the compositional range. AC and DC magnetic measurements identify the nitrides of all compositions as canonical spin glasses with a linear increase of T_g from 4 K for Ge-rich to 9 K for Sn-rich nitrides. The competing magnetic orders were confirmed by DFT calculations.