EQMResearch group
Level 3 · Magnetism in layered materials

Spin-flip transition

B > B_sf

Above a critical magnetic field, AFM layers snap into the FM configuration. This is what re-paints the spin pattern in the simulator.

Build on:Antiferromagnetism (AFM),Ferromagnetism (FM)

Snap from AFM to FM

CrSBr's AFM ground state is held together by a small interlayer coupling. Apply a magnetic field along the easy axis and that coupling can be overcome — at a critical field ±B_sf the spins suddenly flip into the FM configuration.

External field B → (units of B_sf)M / M_sat

Below ±B_sf the antiferromagnetic order holds and the net magnetisation is zero. Cross the threshold and one of the two sub-lattices flips, snapping the sample into a fully ferromagnetic state.

Idealised magnetisation curve: zero magnetisation up to ±B_sf, then a sharp jump to saturation.

Why this matters in the lab

The spin-flip transition is exactly the knob experimenters turn to move the excitonenergy. In the simulator we don't apply a field directly — instead, you sketch the spin pattern that the field would produce, and watch the reflectance respond.

Key takeaways
  • Above ±B_sf the layers snap from AFM to FM.
  • This is the experiment's control knob.
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