A Study of Superconductivity in a Series of Strontium Platinum Phosphides
Jawdat, BenMaan I. 1988-
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In this work, the superconductivity in a series of strontium platinum phosphides was investigated. Three compounds, SrPt3P, SrPt6P2, and SrPt10P4, the latter two of which we discovered, were synthesized and characterized. We studied SrPt3P(1-x)Six resistively, magnetically, and calorimetrically, and found an apparent non-scaling of the Tc with the density of states at the Fermi level N(EF) that can be attributed to a significant weakening of the electron-phonon interaction strength. We found superconductivity in the new structure type SrPt6P2 at Tc = 0.6 K and attribute the lower value of Tc to a weak coupling strength as evidenced by our specific heat measurement and analysis. Superconductivity at Tc = 1.4 K was found in another new structure type compound SrPt10P4 with structural building blocks reminiscent of those from both SrPt3P and SrPt6P2. In SrPt10P4, our specific heat and upper critical field Hc2 measurements indicate the opening of two superconducting gaps Delta1 and Delta2 below Tc. A method of comparing the contributions to superconductivity in different compounds by analysis of the specific heat is developed in which the contribution from the density of states at the Fermi level N(EF) is separated from that of the interaction strength V and is applied to gain insight into the factors driving the superconductivity in these compounds.