  Magnetic nanorings have been widely studied due to their potential
applications in spintronic and magnonic devices. In this work, by means of
analytical calculations and micromagnetic simulations we have analyzed the
magnetic energy of nanorings with variable anisotropy along their radius. Four
magnetic states, including two new magnetic configurations, here called meron
and knot-like states, are considered, looking to the relative lower energy
states as a function of anisotropy. Phase diagrams with this states are
presented.

Mesoscale and Nanoscale Physics