Phonon damping effect during the premartensitic transformation in Heusler alloy Ni 2MnGa

Abstract

An interaction model between two magnons and one transverse acoustic (TA) phonon has been established to investigate the phonon damping effect leading to the softening of TA phonon and elastic modulus during the premartensitic transformation (PT) in Heusler alloy Ni 2MnGa. This kind of damping is found to be of the temperature- and wavevector-dependence. It seems clear that the phonon damping rises relatively steeply at the wavevector corresponding to the observed phonon softening mode due to the magnon–phonon coupling, and will reach its maximum at the PT temperature.