Concepts and steps for the realization of a new domain wall based giant magnetoresistance nanowire device: From the available 24 multiturn counter to a 212 turn counter

Two concepts for new types of a magnetic domain wall (DW) based multiturn counter with true power on functionality are presented. Both counters use several closed loops of magnetic nanowires, each with different numbers of cusps. The turns are counted by the motion of domain walls through the loops, whereas a DW will move through one cusp during 90° external field rotation. Two concepts are introduced: a system based on binary logic, which is easy to integrate in digital electronics, and a system based on coprime numbers, which is useful to count large numbers. We have performed micromagnetic simulations in order to optimize the geometry of the cusp with respect to the operation margin of the device. Experimental verification of the domain wall motion through a giant magnetoresistance stack cusp is given. Furthermore, the read-out scheme for both systems is shown.