Eur. Phys. J. B (2014) 87: 68
https://doi.org/10.1140/epjb/e2014-40265-8

Regular Article

Pressure-induced superconductivity and structural transitions in Ba(Fe_0.9Ru_0.1)₂As₂

¹ Department of Physics, University of Alabama at Birmingham (UAB), Birmingham, AL 35294, USA
² Materials Science and Technology Division, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA
³ Mail Stop L-041, Lawrence Livermore National Laboratory (LLNL), Livermore, CA 94550, USA

^a e-mail: uhoya@uab.edu

Received: 1 April 2013
Received in final form: 12 February 2014
Published online: 19 March 2014

Abstract

Electrical transport and structural characterizations of isoelectronically substituted Ba(Fe_0.9Ru_0.1)₂As₂ have been performed as a function of pressure up to ~30 GPa and temperature down to ~10 K using designer diamond anvil cell. Similar to undoped members of the AFe₂As₂ (A = Ca, Sr, Ba) family, Ba(Fe_0.9Ru_0.1)₂As₂ shows anomalous a-lattice parameter expansion with increasing pressure and a concurrent ThCr₂Si₂ type isostructural (I4/mmm) phase transition from tetragonal (T) phase to a collapsed tetragonal (cT) phase occurring between 12 and 17 GPa where the a is maximum. Above 17 GPa, the material remains in the cT phase up to 30 GPa at 200 K. The resistance measurements show evidence of pressure-induced zero resistance that may be indicative of high-temperature superconductivity for pressures above 3.9 GPa. The onset of the resistive transition temperature decreases gradually with increasing pressure before completely disappearing for pressures above ~10.6 GPa near the T-cT transition. We have determined the crystal structure of the high-T_c phase of Ru-doped BaFe₂As₂ to remain as tetragonal (I4/mmm) by analyzing the X-ray diffraction pattern obtained at 10 K and 9.7 ± 0.7 GPa, as opposed to inferring the structural transition from electrical resistance measurement, as in a previous report [S.K. Kim, M.S. Torikachvili, E. Colombier, A. Thaler, S.L. Bud’ko, P.C. Canfield, Phys. Rev. B 84, 134525 (2011)].