Physics – Condensed Matter
Scientific paper
1999-06-11
Physics
Condensed Matter
28 pages, 15 eps figures, accepted for publication in Phys. Rev. B
Scientific paper
10.1103/PhysRevB.60.7071
The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by including both structural and magnetic degrees of freedom in order to elucidate premartensitic effects. Special attention is paied to the effect of the magnetoelastic coupling in Ni2MnGa. The microscopic model is constructed and justified based on the analysis of the experimentally observed strain variables and precursor phenomena. The description includes the (local) tetragonal distortion, the amplitude of the plane-modulating strain, and the magnetization. The model is solved by means of mean-field theory and Monte Carlo simulations. The results show that a variety of premartensitic effects may appear due to the magnetoelastic coupling. For large values of the magnetoelastic coupling parameter we find a premartensitic first-order transition line ending in a critical point. This critical point is responsible for the existence of large premartensitic fluctuations which manifest as broad peaks in the specific heat, not always associated with a true phase transition. The main conclusion is that premartensitic effects result from the interplay between the softness of the anomalous phonon driving the modulation and the magnetoelastic coupling. In particular, the premartensitic transition occurs when such coupling is strong enough to freeze the involved mode phonon.
Cast'an Teresa
Lindgaard Per-Anker
Vives Eduard
No associations
LandOfFree
Modeling Premartensitic effects in Ni2MnGa: A Mean Field and Monte Carlo Simulation Study does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Modeling Premartensitic effects in Ni2MnGa: A Mean Field and Monte Carlo Simulation Study, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modeling Premartensitic effects in Ni2MnGa: A Mean Field and Monte Carlo Simulation Study will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-705050