Hysteresis loops in spinor Bose-Einstein condensates subject to synthetic gauge fields.

We explore the hysteretic dynamics of spinor Bose-Einstein condensates of ultracold atoms loaded in static 2D ring geometries and subjected to varying synthetic magnetic fields. Electrically neutral, pseudo-spin-1/2 condensates are probed by one-component weak-link potentials that make available paths for the transit of vortices into and out of the ring in both components, and thus can control the number of flux quanta threading the ring hole. For perpendicular fields, domain walls that are dynamically generated in the relative phase of the spin components are shown to play a key role in driving the hysteretic behavior of the whole system through changes in the net magnetic flux. In the presence of spin-orbit coupling, hysteresis is exhibited around the phase transitions found by the metastable current states for varying fields.