Strong Quasi-Particle Renormalization in Praseodymium

The Fermi surface areas and cyclotron masses in praseodymium have been measured by means of the de Haas-van Alphen effect and calculated via the relativistic linear muffin tin orbital technique. The ratios of the measured and calculated masses are found to be unprecedently large for an elemental metal, and they exhibit a strongly anisotropic magnetic-field dependence. The strong-fermion renormalization can be understood in terms of the dynamical f -electron-conduction-electron coupling in the incipient antiferromagnetic state at low temperature. The coupling parameters inferred independently of the magnetic-field dependence of the cyclotron masses and Fermi surface areas are of comparable magnitudes.