Mössbauer and magnetization studies of the NpM2Si2(M=Cr,Mn,Fe,Co,Ni,Cu) systems

Abstract

Magnetization and ${}_{}{}^{237}{}_{}{}^{}\mathrm{Np}$ Mössbauer studies of the tetragonal $\mathrm{Np}{M}_2{\mathrm{Si}}_2$ intermetallic compounds were performed. The compounds exhibit a wide variety of magnetic phenomena. Np${\mathrm{Mn}}_2$ ${\mathrm{Si}}_2$ orders ferromagnetically above 300 K, and has a magnetic hyperfine interaction of 1840(50) MHz at 4.2 K. All other compounds order antiferromagnetically. The Néel points and the magnetic hyperfine interaction in saturation of the $\mathrm{Np}{M}_2{\mathrm{Si}}_2$ compounds are 73(3), 87(3), 42(4), 33(3), 34(3) K and 2800(50), 2535(50), 2300(50), 1730(50), 3430(50) MHz for $M=\mathrm{C}\mathrm{r},\mathrm{F}\mathrm{e},\mathrm{C}\mathrm{o},\mathrm{N}\mathrm{i},\mathrm{a}\mathrm{n}\mathrm{d}\mathrm{C}\mathrm{u}$, respectively. In Np${\mathrm{Cu}}_2$ ${\mathrm{Si}}_2$, the magnetic phase transition is of the first order.