title: Structure and unusual magnetic properties of YbMn0.17Si1.88.
abstract: YbMn0.17Si1.88 was synthesized from the reaction of ytterbium, manganese, and silicon using indium as a flux. The average structure of YbMn0.17Si1.88 was refined in the monoclinic space group P21, with a = 4.0107(8) Å, b = 3.8380(8) Å, c = 14.458(3) Å, β = 97.97(3)°, R1/wR2 = 0.0296/0.0720. The structure can be described as the intergrowth of three AlB2-type layers and one BaAl4-type layer. Magnetic susceptibility measurements suggest that the ytterbium atoms in YbMnxSi2-x exist in a mixed valent or intermediate valent state. YbMn0.17Si1.88 shows weak antiferromagnetic ordering below ∼4.5 K. The magnetic interactions between the Mn and Yb atoms in YbMn0.17Si1.88 are evident from the magnetic susceptibility measurements performed at low field. A negative magnetization is observed on warming and a positive magnetization on cooling. The heat capacity data suggest moderate heavy fermion behavior.
authors.affiliation: Department of Chemistry, Northwestern University, 2145 N. Sheridan Road, Evanston, Illinois 60208-3113, United States.
authors.forename: Sebastian C
authors.initials: SC
authors.lastname: Peter
authors.forename: Christos D
authors.initials: CD
authors.lastname: Malliakas
authors.forename: Mercouri G
authors.initials: MG
authors.lastname: Kanatzidis