Structure and magnetic properties of SmMn{sub 2}(Ge{sub 1{minus}{ital x}}Si{sub {ital x}}){sub 2}

The structure and magnetic properties of SmMn{sub 2}(Ge{sub 1{minus}{ital x}}Si{sub {ital x}}){sub 2} compounds ({ital x}=0{endash}1.0) have been investigated. All the compounds crystallize in ThCr{sub 2}Si{sub 2}-type structure. Substitution of Si for Ge leads to a linear decrease of the lattice constants and the unit-cell volume. In all compounds a transition from the ferromagnetic to the antiferromagnetic state is observed at a lower temperature {ital T}{sub 1}, which first decreases, goes through a minimum at {ital x}=0.4{endash}0.6, and then increases again with Si concentration. As temperature increases, for the compounds with {ital x}{lt}0.3 both a antiferromagnetic{endash}ferromagnetic transition and the ferromagnetic{endash}paramagnetic transitions are observed as well at {ital T}{sub 2} and at the Curie temperature {ital T}{sub {ital c}}, respectively. With increasing Si content the {ital T}{sub {ital c}} decreases, whereas {ital T}{sub 2} increases from 140 K for {ital x}=0 to 215 K for {ital x}=0.2. For compounds with {ital x}{ge}0.3 the antiferromagnetic{endash}paramagnetic transition was observed with increasing temperature and the N{acute e}el temperature increases with increasing Si content. The saturation magnetization at 1.5 K decreases first, goes through a minimum at {ital x}=0.6, and then increases again with increasing Si content. At room temperature, the saturation magnetization decreases monotonicallymore » from 3.27 {mu}{sub {ital B}}/f.u. for {ital x}=0 to nearly zero for {ital x}=0.3. {copyright} {ital 1996 American Institute of Physics.}« less