Spin wave instabilities and field induced transitions in heavy fermions

We study phase transitions in heavy fermion systems due to spin-wave instabilities. One motivation is to determine the changes in the spin-wave parameters of a magnetically ordered heavy fermion system as it approaches a quantum critical point (QCP) by applying pressure. The other more actual is to provide an alternative approach, based on spin-wave instabilities, for the magnetic field induced transitions recently observed in antiferromagnetic heavy fermion materials.