Y3MnAu5: Three Distinctive d-Metal Functions in an Intergrown Cluster Phase

TitleY3MnAu5: Three Distinctive d-Metal Functions in an Intergrown Cluster Phase
Publication TypeJournal Article
Year of Publication2013
AuthorsSamal SL, Pandey A, Johnston DC, Corbett JD
Journal TitleJournal of the American Chemical Society
Date Published01
Type of ArticleArticle
ISBN Number0002-7863
Accession NumberWOS:000313920800063
Keywordsau, chemistry, compound, gold substitution, intermetallic compounds, SODIUM, system, tellurides, tunnels

The new Y3MnAu5 intermetallic phase is obtained from the arc-melted elements in virtually quantitative yields after annealing at 1000 degrees C for similar to 3 d. Its remarkable structure [rhombohedral, R (3) over bar, Z = 6; a = 8.489(1) angstrom, c = 18.144(2) angstrom] consists of a 2:1 cubic-close-packed intergrowth between edge-shared Mn-centered Au rhombohedra (Mn@Au-8) with gold-centered antiprismatic (Au@Y-6) clusters via a common gold network. Magnetic susceptibility (chi) data for Y3MnAu5 were fitted by a Curie-Weiss law. The Curie constant indicates a large effective moment corresponding to nearly localized Mn spins S = 5/2, and the Weiss temperature demonstrates the dominance of ferromagnetic (FM) interactions. An antiferromagnetic (AFM) transition at T-N = 75 K and a possible spin reorientation transition at 65 K were observed. Analysis of the chi data for T < T-N suggests a planar noncollinear helical AFM structure that arises from competing AFM interactions between FM-aligned layers of spins in the ab-plane with a turn angle of 69 degrees between the spins along the helix c-axis. A magnetic field-induced spin flop transition is observed below T-N. Spin-polarized LMTO-LSDA calculations indicate an similar to 2 eV splitting of the Mn 3d states and a metallic ground state, and their COHP analyses demonstrate that similar to 81% of the total Hamilton populations originate from heteroatomic polar Y-Au and Mn-Au bonding. The Mn 3d, Y 4d, and Au 5d characteristics are remarkably diverse: localized and magnetically polarized for Mn; reducing and cationic for Y; and relativistically strongly bonded and oxidizing for Au, bonding of the latter two being broadly delocalized.

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