Crystal Chemistry and Magnetic Behavior of Compounds RE3Mn4Sn4, RE = La, Ce, Pr, Nd, Sm and MM (Mischmetal)

Novel ternary stannides RE3Mn4Sn4 have been synthesized by the arc melting technique, starting from the pure elements. All compounds with the early and large rare earth metals (RE = La, Ce, Pr, Nd, Sm) and mischmetal (MM) were found to be isotypic with the Gd3Cu4Ge4-type (space group, Immm-D2h25, No. 71; Z = 2). The crystal structure of the Gd3Cu4Ge4-type stannides is a combination of structural slabs RESn2 of the AlB2-type and slabs RE4Mn2Sn2, common to the ThCr2Si2type. The (Ce, Pr, Nd, Sm)3Mn4Sn4 compounds exhibit antiferromagnetism. For (Pr, Nd)3Mn4Sn4 an onset of a spinflip process is indicated at a magnetic field Hcrit > 2.5 Tesla. La3Mn4Sn4 as well as Ce3Mn4Sn4 show broad maxima of the susceptibility at T ∼ 300 K, possibly due to demagnetizing effects caused by valence instabilities. The manganese atoms carry localized effective moments of 3 μB and 5 μB, respectively.