Magnetic droplet solitons in orthogonal spin valves
2015 (English)In: Fizika Nizkih Temperatur, ISSN 0132-6414, E-ISSN 1816-0328, Vol. 41, no 10, 1063-1068 p.Article in journal (Refereed) Published
We review the recent experimental advancements in the realization and understanding of magnetic droplet solitons generated by spin transfer torque in orthogonal nanocontact based spin torque nanooscillators (STNOs) fabricated on extended spin valves and spin valve nanowires. The magnetic droplets are detected and studied using the STNO microwave signal and its resistance, the latter both quasistatically and time-resolved. The droplet nucleation current is found to have a minimum at intermediate magnetic field strengths and the nature of the nucleation changes gradually from a single sharp step well above this field, mode-hopping around the minimum, and continuous at low fields. The mode-hopping and continuous transitions are ascribed to droplet drift instability and re-nucleation at different time scales, which is corroborated by time-resolved measurements. We argue that the use of tilted anisotropy fixed layers could reduce the nucleation current further, move the nucleation current minimum to lower fields, and potentially remove the need for an applied magnetic field altogether. Finally, evidence of an edge mode droplet in a nanowire is presented.
Place, publisher, year, edition, pages
2015. Vol. 41, no 10, 1063-1068 p.
Magnetic droplet soliton, Magnetoresistance, Perpendicular anisotropy, Spin torque, Anisotropy, Magnetic devices, Magnetic fields, Magnetism, Nanowires, Nucleation, Solitons, Applied magnetic fields, Continuous transitions, Magnetic droplets, Magnetic field strengths, Spin transfer torque, Time resolved measurement, Drops
IdentifiersURN: urn:nbn:se:kth:diva-175047ScopusID: 2-s2.0-84941777305OAI: oai:DiVA.org:kth-175047DiVA: diva2:877439
QC 201512072015-12-072015-10-092015-12-07Bibliographically approved