Electronic Chern number dynamics driven by phase shifts in multiple-Q textures

Pascal Prass¹, Fabian R. Lux¹, Duco van Straten², Yuriy Mokrousov^1,3

¹ Institute of Physics, Johannes Gutenberg University Mainz, Germany
² Institute of Mathematics, Johannes Gutenberg University Mainz, Germany
³ Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, Germany

A multiple-q spin texture is given by the superposition of multiple spin spirals and gives rise to a periodic array of topological spin structures, such as skyrmions. Little is known about the electronic structure of multi-q states, in particular in the context of the interplay of real and quasi-momentum space topology. Using an algebraic approach from noncommutative K-Theory, we recently developed a method to assign mixed space Chern numbers to the gaps in the electronic spectrum of multi-q magnets [1]. In recent works [2,3] it was illustrated how tuning the relative phase shifts of the spin waves as well as the textures' net magnetization leads to topological phase transitions in the spin texture, i.e., integer jumps of its winding number. These significant discontinuous jumps in the real-space topology contribute to the mixed-space Chern numbers and, thus, let us implicitly deduce the behavior of the quasi-momentum topology. We directly investigate the spin textures' electronic topology to determine the relationship between its real-space winding number and quasi-momentum space Chern numbers. Understanding the evolution of electronic structure during these transitions will have far-reaching implications for developing tunable topological Hall devices.

 

Reference(s)
[1] F. Lux et al. arXiv:2103.0104 (2021).
[2] K. Shimizu et al. arXiv:2201.03290 (2022).
[3] S. Hayami et al. Nat. Commun. 12, 6927 (2021).