Spin fluctuation driven structural phase transitions in itinerant electron magnets:: γ → α transition in Ce-based compounds

We suggest a novel mechanism of structural transitions in itinerant electron magnets, driven by spin fluctuations strongly coupled to the crystal lattice. The mechanism explains the isostructural gamma -> alpha transition in Ce-based compounds. The high-temperature gamma-phase is shown to be stabilized by spin fluctuations dominating the bulk modulus. With the decrease of temperature and spin fluctuation amplitudes the bulk modulus becomes negative giving rise to a structural instability. The structural phase transition to the low-temperature alpha-phase is accompanied by the change of the volume described in terms of the order parameter defined by the volume strain. (c) 2007 Elsevier B.V All rights reserved.