External bias field control of skyrmion dynamics in a magnetic nanotrack

Evolution and tunable control of skyrmion dynamics in a magnetic nanotracks are crucial for the next generation skyrmion based racetrack memory (RM) devices. Here, using micromagnetic simulation we present the precise control of skyrmion motion in a magnetic nanotrack consisting of three narrow and a wider nanochannels under the influence of spin transfer torque (STT) and out of plane bias field. We find that the application of out of plane magnetic field results in efficient conversion of Domain wall (DW) pair to skyrmion as well as assists in achieving the uniform velocity of each skyrmion. Importantly, the thorough analysis of individual and total energy terms during the DW pair to skyrmion conversion provides in-depth insight into the role of bias field in overcoming the pinning potential present at the junction of the narrow and wide nanochannel. The precise control of skyrmion motion stabilized from a DW pair under the influence of external bias field is significantly important for the development of skyrmion based memory devices.