EQMResearch group
Level 5 · CrSBr & the experiment

CrSBr

Cr S Br

A layered van der Waals semiconductor with strong in-plane FM order and AFM coupling between layers — a near-ideal magnetic 2D crystal.

Build on:Semiconductors & band gap,2D / van der Waals magnets,Antiferromagnetism (AFM)

The material

CrSBr (chromium sulfide bromide) is a layered van der Waals semiconductor with a band gap around 1.5 eV. Its standout features:

  • A-type antiferromagnet: ferromagnetic in-plane, antiferromagnetic between layers (↑↓↑↓ down the stack).
  • Bright, sharp exciton: a dominant absorption feature at ~1.375 eV, ideal for cavity-coupling experiments.
  • Magnetism couples to optics: the exciton energy depends on the local spin order — flip the spins, move the dip.
sheets↕ van der Waals gap (~3 Å)
Side view: rigid magnetic sheets stacked by weak vdW forces, with one spin per sheet that we track as the simulator's input.

Why it's a good lab rat

Most magnets are not optically clean: they absorb broadly, scatter badly, or have no sharp transitions to talk about. CrSBr is a rare counter-example — clean optical response and tunable magnetic order in the same material.

Key takeaways
  • CrSBr = layered vdW semiconductor + A-type AFM order.
  • Exciton at ~1.375 eV is sensitive to spin arrangement.
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