Superconductivity of the ternary ruthenium compounds HfRuP and ZrRuX (X = P, As, Si or Ge) prepared at a high pressure

Abstract

Abstract Using a wedge-type cubic-anvil high-pressure apparatus, equiatomic Ru compounds HfRuP and ZrRuX (X = P, As, Si or Ge) with layered structures have been prepared at high temperatures and high pressures. The super-conducting transition teinperatures T c of these compounds were 12 K for HfRuP, 13 K for ZrRuP, 11.5K for ZrRuAs, 12.2 K for ZrRuSi and 10.5 K for ZrRuGe. The electrical resistivities of these ternary Ru compounds have been measured as functions of applied magnetic field at low temperatures. The upper critical fields H c2 of HfRuP, ZrRuP, ZrRuAs, ZrRuSi and ZrRuGe are 14, 16, 14.1, 14.5 and 8.3 T respectively. The value of H c2 for ZrRuP is the highest among the equiatomic Ru compounds. The coherence lengths of these compounds are 48.5 Å for HfRuP, 45.4 Å for ZrRuP, 48.3 Å for ZrRuAs, 47.7 Å for ZrRuSi and 63.0 Å for ZrRuGe. The superconductivity of the ternary Ru compounds is discussed.