Magnetization ground state and reversal modes of magnetic nanotori
  In this work, and by means of micromagnetic simulations, we study the magnetic properties of toroidal nanomagnets. The magnetization ground state for different values of the aspect ratio between the toroidal and polar radii of the nanotorus has been obtained. The hysteresis curves are also obtained, evidencing the existence of two reversal modes depending on the geometry: a vortex mode and a coherent rotation. A comparison between toroidal and cylindrical nanoparticles has been performed evidencing that nanotori can accommodate a vortex as the ground state for smaller volume than cylindrical nanorings. This is important because if vortices are used as bits of information, nanotori allow a higher density data storage. 
Smiljan Vojkovic, \'Alvaro S. N\'u\~nez, Dora Altbir and Vagson L.   Carvalho-Santos
cond-mat.mes-hall