Nanowerk October 5, 2020
The fast creation of topological phases in matter requires massive reorientation of charge or spin degrees of freedom. An international team of researchers (Germany, Belgium, USA – MIT, Italy, the Netherlands) report the picosecond emergence of an extended topological phase that comprises many magnetic skyrmions. The nucleation of this phase, followed in real time via single-shot soft X-ray scattering after infrared laser excitation, is mediated by a transient topological fluctuation state. This state is enabled by the presence of a time-reversal symmetry-breaking perpendicular magnetic field and exists for less than 300 ps. Atomistic simulations indicate that the fluctuation state largely reduces the topological energy barrier and thereby enables the observed rapid and homogeneous nucleation of the skyrmion phase. These observations provide fundamental insights into the nature of topological phase transitions and suggest a path towards ultrafast topological switching in a wide variety of materials through intermediate fluctuating states. The research opens a new chapter in topology research. Interestingly, this discovery also offers an additional method to achieve more efficient magnetic data storage…read more. TECHNICAL ARTICLE
Artistic illustration of skyrmions (coloured spheres) during the chaotic phase in the magnet, enabling much faster switching than previously known. Credit: Dr. Bastian Pfau, Max-Born-Institut Berlin