Chemical Pressure Effect and Dimer Formation in (Ba,Sr)Ni$_2$As$_2$ Solid Solutions

ORAL

Abstract

Although both BaNi$_2$As$_2$ and SrNi$_2$As$_2$ form in ThCr$_2$Si$_2$ structure, these materials display very different behaviors, owing in part to an important structural difference: while the Sr compound exhibits As-As bonds between layers, the Ba compound lacks these interlayer bonds. Thus, substitution of Sr into BaNi$_2$As$_2$ produces a positive chemical pressure effect on the system that pulls the NiAs layers closer together and towards As-As dimer formation. We will present the resulting phase diagram as determined by x-ray, chemical composition, electrical resistivity and magnetization measurements.

*This work was supported by AFOSR-MURI FA9550-09-1-0603.

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Authors

  • Tyler Drye

    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland-College Park
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742

  • Shanta R. Saha

    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland-College Park
    • Ceter for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742

  • Johnpierre Paglione

    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland-College Park
    • Ceter for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742
    • University of Maryland
    • Department of Physics, University of Maryland
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742
    • Center for Nanophysics and Advanced Materials, Dept. of Physics, University of Maryland, College Park