Wed, Apr 24
4:00 PM — 5:00 PM
Marshak ScienceThe City College of New York160 Convent Ave., New York, NY 10031
Marshak Science, 418N
"The ferromagnetic random field Ising model"Physics Colloquium
SPEAKER: Dr. Moshe Schechter, Ben Gurion University
Title: "The ferromagnetic random field Ising model"
The random field Ising model is central to the study of disordered systems. The model describes well various physical, biological, and even social systems, but for long its realization in ferromagnetic systems was hindered by the difficulty to produce locally random magnetic fields. Recently it was shown that locally random effective longitudinal fields can be realized in anisotropic dipolar systems, in both their ferromagnetic and spin glass phases. Experiments on single molecule magnets and rare earth insulators have revealed a sharp, nearly linear, decrease of the critical ferromagnetic temperature with random field. In this talk I discuss the significance of the presence of competing interactions and an underlying spin-glass phase in the disordering of ferromagnetic systems. A novel disordering mechanism is introduced, and used to explain the above mentioned experimental results.