Tunable Single-Ion Anisotropy In Spin-1 Models Realized With Ultracold Atoms

Mott insulator plateaus in optical lattices are a versatile platform to study spin physics. Using sites occupied by two bosons with an internal degree of freedom, we realize a uniaxial single-ion anisotropy term proportional to (S-z)(2) that plays an important role in stabilizing magnetism for low-dimensional magnetic materials. Here we explore nonequilibrium spin dynamics and observe a resonant effect in the spin alignment as a function of lattice depth when exchange coupling and on-site anisotropy are similar. Our results are supported by many-body numerical simulations and are captured by the analytical solution of a two-site model.