Stoner–Wohlfarth Switching Astroid

The Stoner–Wohlfarth model describes the behavior of a single-domain ferromagnet exhibiting uniaxial magnetic anisotropy. It provides an elegant way to trace the coherent-magnetization boundary where a metastable energy minimum disappears.

Experiment

You can interactively explore the astroid boundaries and magnetization regimes. Navigate to the interactive Stoner–Wohlfarth Switching Astroid module and try the following:

1. Change the "Field angle degrees" select control to "30".
2. Set the "Field magnitude" select control to "0.5".
3. Observe the visual plot updates. The applied vector (blue dot) falls inside the boundary curve, yielding a negative residual and indicating the "Inside" regime.
4. Increase the "Field magnitude" to "1". The vector now falls outside the boundary (positive residual), moving to the "Outside" regime where the original metastable state has collapsed.