Speaker
Description
The kagome dipolar spin ice presents a rich phase diagram with intriguing magnetic properties. In particular, the so-called spin ice II phase is characterized by a very unusual behavior: magnetic order and magnetic disorder coexist at thermodynamic equilibrium. This coexistence of order and disorder can be visualized in real space: although a magnetic configuration belonging to the spin ice II phase does not show any obvious ordered spin pattern, the magnetic charge associated with the dumbbell description of the magnetic moment does crystallize. As the concept of magnetic charge is directly linked to the magnetic moment, charge ordering implies spin ordering.
Reaching such a phase in a large lattice is very difficult experimentally, if even possible. This is so because the relevant spin dynamics to enter the ice II regime is characterized by loop moves, in which an open or closed loop of spins reverses in a single event. However, this type of collective motion is statistically very unlikely. Real space imaging of the spin ice II phase and of the long range order ground state thus appears as a lost battle. We will show in this contribution that this is not quite true as experimental tricks might be used to force the system entering the long range order ground state, with no defect over a large amount of spins. The system can then be intentionally disordered to 'warm up' the array and bring it into the ice II manifold.
