Structural phase transition above the superconducting dome in Co-substituted BaNi$_2$As$_2$

ORAL

Abstract

BaNi$_2$As$_2$ is a Ni-pnictide superconductor ($T_c$$\sim$0.7K) which also shows a first-order tetragonal to triclinic structural phase transition ($T_s$$\sim$135K). With cobalt substitution, resistivity measurements show that the structural phase transition is suppressed as a dome shaped superconducting phase emerges. Using x-ray reciprocal space mapping, we present a direct measurement on the structural phase transition of Ba(Ni$_{2-\text{x}}$Co$_\text{x}$)2As2 (x=0, 0.15, 0.3). In contrast to the undoped (x=0) system, which shows a small hysteresis, the optimally doped (x=0.15) system with highest $T_c$$\sim$2.5K exhibits a coexistence of tetragonal and triclinic phase over a wide range of temperature from 75K to 15K. This result implies a strong correlation between the structural instability and superconductivity.

*XRD measurements were supported by DOE-BES grant # DE-FG02-06ER46285.

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Authors

  • Sangjun Lee

    • University of Illinois at Urbana-Champaign
    • Univ of Illinois - Urbana

  • Gilberto de la Pena Munoz

    • University of Illinois at Urbana
    • University of Illinois at Urbana-Champaign
    • Univ of Illinois - Urbana

  • Stella Sun

    • Univ of Illinois - Urbana

  • Chris Eckberg

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

  • Daniel Campbell

    • Univ of Maryland-College Park

  • Tyler Drye

    • Univ of Maryland-College Park

  • Hyunsoo Kim

    • Univ of Maryland-College Park

  • Peter Zavalij

    • Univ of Maryland-College Park

  • Phil Piccoli

    • Univ of Maryland-College Park

  • Jeff Lynn

    • NIST Gaithersburg

  • Johnpierre Paglione

    • Univ of Maryland-College Park
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park 20742, USA
    • University of Maryland
    • Department of Physics, University of Maryland, MD, USA; Canadian Institute for Advanced Research
    • Center for Nanophysics and Advanced Materials, Department of Physics, University of Maryland, College Park, MD 20742, USA

  • Peter Abbamonte

    • Univ of Illinois - Urbana
    • University of Illinois at Urbana
    • University of Illinois at Urbana-Champaign