Probing Coherences and Itinerant Magnetism in a Dipolar Lattice Gas

We report on the study of itinerant magnetism of lattice-trapped magnetic atoms, driven by magnetic dipole-dipole interactions, in the low-entropy and close-to-unit filling regime. We have used advanced dynamical decoupling techniques to efficiently suppress the sensitivity to magnetic field fluctuations. We have thus measured the spin coherence of an itinerant spin 3 Bose dipolar gas throughout a quantum phase transition from a superfluid phase to a Mott insulating phase. In the superfluid phase, a metastable ferromagnetic behavior is observed below a dynamical instability that occurs at lattice depths below the phase transition. In the insulating phase, the thermalization toward a paramagnetic state is driven by an interplay between intersite and superexchange interactions.