Fermi-surface topology of the iron pnictide LaFe₂P₂

We report on a comprehensive de Haas-van Alphen (dHvA) study of the iron pnictide LaFe₂P₂. Our extensive density-functional band-structure calculations can well explain the measured angular-dependent dHvA frequencies. As salient feature, we observe only one quasi-two-dimensional Fermi-surface sheet; i.e., a hole-like Fermi-surface cylinder around Gamma, essential for s_+/- pairing, is missing. In spite of considerable mass enhancements due to many-body effects, LaFe₂P₂ shows no superconductivity. This is likely caused by the absence of any nesting between electron and hole bands.