  The dynamical properties of skyrmions can be exploited to build devices with
new functionalities. Here, we first investigate a skyrmion-based ring-shaped
device by means of micromagnetic simulations and Thiele equation. We
subsequently show three applications scenarios: (1) a clock with tunable
frequency that is biased with an electrical current having a radial spatial
distribution, (2) an alternator, where the skyrmion circular motion driven by
an engineered anisotropy gradient is converted into an electrical signal, and
(3) an energy harvester, where the skyrmion motion driven by a thermal gradient
is converted into an electrical signal, thus providing a heat recovery
operation. We also show how to precisely tune the frequency and amplitude of
the output electrical signals by varying material parameters, geometrical
parameters, number and velocity of skyrmions, and we further prove the correct
device functionality under realistic conditions given by room temperature and
internal material defects. Our results open a new route for the realization of
energy efficient nanoscale clocks, generators, and energy harvesters.
