Formation of collapsed tetragonal phase in EuCo$_{2}$As$_{2}$ under high pressure

ORAL

Abstract

The structural properties of EuCo$_{2}$As$_{2}$ have been studied up to 35 GPa, through the use of x-ray diffraction in a diamond anvil cell at a synchrotron source. At ambient conditions, EuCo$_{2}$As$_{2}$ ($I$4/\textit{mmm}) has a tetragonal lattice structure with a bulk modulus of 48 $\pm $ 4 GPa. With the application of pressure, the $a $axis exhibits negative compressibility with a concurrent sharp decrease in $c$-axis length. The anomalous compressibility of the $a $axis continues until 4.7 GPa, at which point the structure undergoes a second-order phase transition to a collapsed tetragonal (CT) state with a bulk modulus of 111 $\pm $ 2 GPa. We found a strong correlation between the ambient pressure volume of 122 parents of superconductors and the corresponding tetragonal to collapsed tetragonal phase transition pressures.

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Authors

  • Matthew Bishop

    University of West Georgia (UWG), Carrollton, GA 30118, USA

  • Walter Uhoya

    University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA

  • Georgiy Tsoi

    University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA, University of Alabama at Birmingham

  • Yogesh Vohra

    Department of Physics, University of Alabama at Birmingham, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA, University of Alabama at Birmingham

  • A.S. Sefat

    ORNL, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory, MST Division, Oak Ridge National Laboratory, ORNL, Oak Ridge, TN, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA, Materials Science \& Technology Division, ORNL, Oak Ridge, TN 37831, USA

  • B.C. Sales

    ORNL, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA, Materials Science \& Technology Division, ORNL, Oak Ridge, TN 37831, USA