Specific heat of metastable Zr1-xSix alloys

Abstract

Non-equilibrium phases in the system Zr1-xSix prepared by liquid quenching are superconducting with intermediate electron-phonon coupling as determined from specific heat, low-field DC magnetisation and electrical resistance measurements. Analysis of the authors data clearly shows that amorphous samples (0.12<or=x<or=0.20) are more homogeneous compared to samples of a metastable BCC phase (0.08<or=x<or=0.11). In the latter samples, a minority phase, presumably amorphous, strongly influences the superconducting properties. The concentration dependence of the transition temperature Tc of the majority phase is dominated by the electronic density of states. The data at very low temperatures suggest the existence of a linear specific heat contribution which may be due to the presence of two-level tunnelling states in both places.