Disorder contra Mermin-Wagner-Hohenberg Effect: From Classical Spin Systems to Ultracold Atomic Gases

Jan Wehr (1) , Armand Niederberger (2) , Laurent Sanchez-Palencia (3) , Maciej Lewenstein (2, 4)

1 Department of Mathematics [University of Arizona]
2 UNIROUEN - Université de Rouen Normandie
3 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique
4 ITP - Institut für Theoretische Physik [Hannover]

We propose a general mechanism of random-field-induced order (RFIO) by studying a case of classical ferromagnetic XY model in a random uniaxial field which breaks the continuous symmetry of the model. We prove rigorously that the system has spontaneous magnetization at temperature T=0, and we present strong evidence that this is also the case for small T>0. We discuss generalizations of this mechanism to various classical and quantum systems. Our results shed light on controversies in existing literature, and open the way to realize RFIO with ultracold atoms in an optical lattice.

Mots clés: disorder; random; spin; ultracold; XY; Heisenberg; optical lattice; Bose-Einstein

Domaines: Autre [cond-mat.other]

Jan Wehr, Armand Niederberger, Laurent Sanchez-Palencia, Maciej Lewenstein. Disorder contra Mermin-Wagner-Hohenberg Effect: From Classical Spin Systems to Ultracold Atomic Gases. 2006. ⟨hal-00022177v3⟩