Modul:   MAT673  Seminar PDE and Mathematical Physics

The free energy of the quantum Heisenberg ferromagnet: validity of the spin wave approximation

Talk by Prof. Dr. Alessandro Giuliani

Speaker invited by: Prof. Dr. Benjamin Schlein

Date: 12.05.14  Time: 17.15 - 19.00  Room: Y27H25

We consider the quantum Heisenberg ferromagnet in three dimensions. We present the first rigorous proof of validity of the spin-wave approximation at low temperatures, at the level of the system's free energy. The proof combines a bosonic formulation of the model induced by the Holstein-Primakoff representation with probabilistic estimates, localization bounds and functional inequalities. Joint work with Michele Correggi and Robert Seiringer.