Highly sensitive band structure of the Stoner-enhanced Pauli paramagnet SrCo₂P₂

The compound SrCo₂P₂ is a Pauli paramagnet very close to ferromagnetic order. To study its electronic structure in close vicinity to the Fermi level, we report measurements of the de Haas–van Alphen effect in magnetic fields up to 35 T in combination with density-functional-theory band-structure calculations in different approximations. The resulting electronic band structure not only depends significantly on the choice of the functional, but also crucially on the exact values of the structural parameters that have been determined at low temperatures by synchrotron x-ray diffraction. We find the best correspondence between the measured and the calculated de Haas–van Alphen frequencies for the general gradient approximation functional and the structural parameters that were determined at 10 K. Although SrCo₂P₂ crystallizes in the uncollapsed tetragonal structure with a large P-P distance between the CoP₂ layers, we observe a rather three-dimensional Fermi-surface topology. We obtain a mass-enhancement factor of about 2 deduced from the ratio between experimental and calculated quasiparticle masses. The temperature dependence of the structural parameters leads to a significant reduction of the electronic density of states at the Fermi level and in comparison with the measured Sommerfeld coefficient to an overall mass renormalization in line with our experiment.