Controlling Skyrmion Lattice Orientation with Local Magnetic Field Gradients

TL;DR

This paper presents a minimally invasive method using magnetic force microscopy to nucleate, manipulate, and reorient skyrmion lattices in soft magnetic materials, enabling controlled studies of their phase behavior and lattice properties.

Contribution

It introduces a simple technique to control skyrmion lattice formation, orientation, and order in soft magnetic films through local magnetic field gradients from MFM scans.

Findings

Reversible transition from stripe domains to skyrmions induced by MFM tip

Systematic improvement in lattice order with repeated scanning

Deterministic rotation of lattice orientation by changing scan direction

Abstract

Precise control over the formation and arrangement of magnetic skyrmion lattices is essential for understanding their emergent behavior and advancing their integration into spintronic and magnonic devices. We report on a simple and minimally invasive technique to nucleate and manipulate skyrmion lattices in soft magnetic CoFeB using single-pass magnetic force microscopy (MFM). By tuning the scan-line spacing to match the intrinsic stripe domain periodicity, the stray field gradient from the MFM tip induces reversible transitions from stripe domains to isolated skyrmions and locally ordered lattices. The resulting skyrmion positions are extracted to compute the local orientational order parameter $\psi_6$, enabling quantitative evaluation of lattice ordering. A systematic improvement in $\langle |\psi_6| \rangle$ is observed with repeated scanning, indicating a transition from a disordered state to ordered hexagonal lattices. Furthermore, we demonstrate that the lattice orientation can be deterministically rotated by changing the scanning direction, as confirmed by both real-space analysis and fast Fourier transformations. This method enables the controlled creation, reordering, and deletion of metastable skyrmion textures on demand. Our approach establishes a practical and accessible platform for studying two-dimensional phase behavior in topological spin systems, offering direct and reconfigurable control over lattice symmetry, order, and orientation.