Congratulations on successful PhD defense to Dr. Ajesh Gopi!

“Exploring complex magnetism in van der Waals materials has been a fascinating journey, revealing how subtle structural features can create entirely new magnetic states such as spin glasses and skyrmions.”

Title: “Complex Magnetism in 2D van der Waals Magnets”

Ajesh’s thesis explores how magnetism behaves in two-dimensional (2D) ferromagnetic van der Waals materials, with a focus on unusual magnetic states called topological spin textures. He studied two members of the Fe_xGeTe₂ family: Fe₅GeTe₂ and Fe₃GeTe₂. In Fe₅GeTe₂, structural and magnetic measurements show that, although the crystal structure lacks inversion symmetry, it does not generate strong enough Dzyaloshinskii–Moriya interaction to form chiral textures. Instead, Lorentz transmission electron microscopy reveals unconventional, mostly non-chiral magnetic bubbles. In Fe₃GeTe2, Ajesh finds that structural features can induce sufficient Dzyaloshinskii–Moriya interaction to stabilise Néel-type skyrmions and, remarkably, a spin-glass state arising from disordered Fe atoms in the van der Waals gap – a rare example in low dimensions. Combining X-ray diffraction, LTEM, magnetic force microscopy, Kerr microscopy, magnetometry, and modelling, the work links crystal structure to complex magnetism and points to new possibilities for spintronic devices.