  Magnetic skyrmions are promising candidates as elementary nanoscale bits in
logic-in-memory devices, intrinsically merging high density memory and
computing capabilities. Here we exploit the dynamics of skyrmions interacting
with anisotropy energy barriers patterned by ion irradiation to design
programmable logic gates. Using micromagnetic simulations with experimental
parameters, we show that a fine tuning of the barrier height and width allows
the selective tunneling of skyrmions between parallel nanotracks triggered by
skyrmion-skyrmion interaction. This can be leveraged to design skyrmion
De-multiplexer (DMux) logic gate which works solely using skyrmions as logic
inputs. By cascading and connecting demultiplexer gates with a specific
topology, we develop a fully programmable logic gate capable of producing any
possible logic output as a sum of all minterms generated by a given set of
inputs without requiring any complex additional electric/magnetic
interconversion. The proposed design is fully conservative and cascadable and
paves a new pathway for full skyrmionic-based logic-in-memory devices.
