"Skyrmion fluctuations at a first-order phase transition boundary"

V. Esposito: X. Y. Zheng, M. H. Seaberg, S. A. Montoya, B. Holladay, A. H. Reid, R. Streubel, J. C. T. Lee, L. Shen, J. D. Koralek, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, P. Fischer, W. Colocho, A. Lutman, F.-J. Decker, S. K. Sinha, E. E. Fullerton, S. D. Kevan, S. Roy, M. Dunne, and J. J. Turner; Applied Physics Letters, 05/04/20.

Additional Authors: X. Y. Zheng, M. H. Seaberg, S. A. Montoya, B. Holladay, A. H. Reid, R. Streubel, J. C. T. Lee, L. Shen, J. D. Koralek, G. Coslovich, P. Walter, S. Zohar, V. Thampy, M. F. Lin, P. Hart, K. Nakahara, P. Fischer, W. Colocho, A. Lutman, F.-J. Decker, S. K. Sinha, E. E. Fullerton, S. D. Kevan, S. Roy, M. Dunne, and J. J. Turner

Abstract:

Magnetic skyrmions are topologically protected spin textures with promising prospects for applications in data storage. They can form a lattice state due to competing magnetic interactions and are commonly found in a small region of the temperature—magnetic field phase diagram. Recent work has demonstrated that these magnetic quasi-particles fluctuate at the μeV energy scale. Here, we use a coherent x-ray correlation method at an x-ray free-electron laser to investigate these fluctuations in a magnetic phase coexistence region near a first-order transition boundary where fluctuations are not expected to play a major role. Surprisingly, we find that the relaxation of the intermediate scattering function at this transition differs significantly compared to that deep in the skyrmion lattice phase. The observation of a compressed exponential behavior suggests solid-like dynamics, often associated with jamming. We assign this behavior to disorder and the phase coexistence observed in a narrow field-window near the transition, which can cause fluctuations that lead to glassy behavior.