Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany
Abstract:
Superconductivity of compressed, high-purity platinum powder (average grain size 2–3 μm) was found by measurements of resistivity, AC susceptibility and magnetization. The transition temperature into the superconducting state Tc and the critical magnetic field Bc strongly depend on the packing fraction f of the samples: we found 0.62Tc(0)1.38 mK and 6.6Bc(0)67 μT for 0.8f0.5, respectively. The temperature dependence of the critical magnetic fields can be described by Bc(T)=Bc(0)(1−(T/Tc)2). The discussion of these results includes possible explanations for the origin of superconductivity in this new superconducting material.