Università Cattolica del Sacro Cuore - Sede di Brescia

Dipartimento di Matematica e Fisica “Niccolò Tartaglia”

Ferromagnetism in finite spin chains

Superradiance transition and Transport through nanostructures

Abstract

 In this talk we will review some research topics we have been working on in the last years. 
 First we will focus on many body spin systems with anisotropy showing the existence
 of a topological non-connectivity threshold and its consequence on statistical properties and
 magnetic reversal times, which are essential to understand the origin of ferromagnetism in
 finite systems.

In the second part of the talk, using an energy-independent non-Hermitian Hamiltonian approach to open systems, we fully describe transport through a sequence of potential barriers as external barriers are varied. Analyzing the complex eigenvalues of the non-Hermitian Hamiltonian model, a transition to a superradiant regime is shown to occur. Transport properties undergo a strong change at the superradiance transition, specifically a drastic change in the structure of resonances is demonstrated.

Relatore

Dr. Luca Celardo

Università Cattolica del Sacro Cuore

Giovedì 15 ottobre 2009

ore 16.00, Aula 10

Via dei Musei, 41 - Brescia