  We report manipulation of the magnetic states of elliptical cobalt
magnetostrictive nanomagnets (of nominal dimensions ~ 340 nm x 270 nm x 12 nm)
delineated on bulk 128{\deg} Y-cut lithium niobate with Surface Acoustic Waves
(SAWs) launched from interdigitated electrodes. Isolated nanomagnets that are
initially magnetized to a single domain state with magnetization pointing along
the major axis of the ellipse are driven into a vortex state by surface
acoustic waves that modulate the stress anisotropy of these nanomagnets. The
nanomagnets remain in the vortex state until they are reset by a strong
magnetic field to the initial single domain state, making the vortex state
non-volatile. This phenomenon is modeled and explained using a micromagnetic
framework and could lead to the development of extremely energy efficient
magnetization switching methodologies.
