Magnetic skyrmions and antiskyrmions are nanoscale spin textures that could encode information, but they decay. At room temperature, thermal fluctuations kick the system over energy barriers, and the soliton unravels. The standard approach to longer lifetimes is higher barriers — stronger pinning, thicker films, heavier atoms. More wall, longer life.
This paper finds a different lever: the shape of the saddle point. In transition-state theory, the decay rate depends not just on the barrier height but on the curvature of the saddle — how quickly the energy landscape falls away from the transition state. A sharp saddle means the system crosses quickly once it reaches the top. An extended saddle — flat in some directions — means the system lingers, and the entropic prefactor that usually accelerates decay is suppressed.
Anisotropic Dzyaloshinskii-Moriya interaction in oxidized Fe₃GeTe₂ creates exactly this geometry. The saddle points governing antiskyrmion collapse are extended: flat along certain directions in configuration space. The entropic contribution to the activation rate is completely suppressed, making the lifetime effectively temperature-independent over a wide range. The result is five orders of magnitude longer lifetimes at room temperature compared to conventional thin-film skyrmions — not from taller walls but from flatter hilltops.
The mechanism inverts the usual intuition. Stability comes not from how hard it is to reach the transition state but from how the transition state is shaped once you're there. The geometry of the escape route matters more than its height.