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PGI-1 Talk: Prof. Dr. Christos Panagopoulos

Tunable Roon Temperature Skyrmions

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07 May 2018 10:30
venue
PGI Lecture Hall

Nanyang Technological University in Singapore

Abstract:

Using particle-like spin structures as a paradigm, I will argue the states induced by engineering spin orbit coupling and inversion symmetry breaking open a broad perspective, with significant impact in the practical technology of spin topology. In one such example, multilayers of Ir/Fe(x)/Co(y)/Pt enable us tailor the magnetic interactions governing skyrmion (Sk) properties, thereby tuning their thermodynamic stability parameter by an order of magnitude. Sk’s are found to exhibit a smooth crossover between isolated (metastable) and disordered lattice configurations across samples, while their size and density can be tuned by factors of 2 and 10, respectively.

For a systematic investigation of the magnetization dynamics, we determined the damping parameter characterizing the magnetization response, and identified a gyrotropic Sk excitation that persists over a wide range of temperatures and across varying sample compositions. Furthermore, to tailor the phenomenology of nanoscale Sk’s, including topological stability and malleability we studied their formation and evolution at zero field through confinement effects. The zero field Sk size can be as small as 50 nm, and varies by a factor of 4 with dot size and magnetic parameters.
Next, to explore the interaction of skyrmions with electrical current I will introduce a detailed microscopic investigation which allowed us identify magnetic structures forming via Sk-Sk interaction and their role in designing and interpreting electrical signatures in materials and devices hosting Sk’s. In particular, we establish direct correspondence between Sk’s and their topological Hall signature in multilayer films by combining transport and magnetic force microscopy measurements over a wide range of temperature and magnetic field.

Contact

Prof. Dr. Stefan Blügel
Phone: +49 2461 61-4249
Fax: +49 2461 61-2850
email: s.bluegel@fz-juelich.de

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