Probing Short-Range Correlations in the van der Waals Magnet CrSBr by Small-Angle Neutron Scattering

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Layered metamagnet CrSBr exhibits unique magnetic, optical, and electrical properties tunable to the 2D limit.
• Research on magnetic van der Waals materials primarily focuses on long-range magnetic order, with short-range correlations less explored.

Purpose of the Study:

• To investigate the formation and characteristics of short-range magnetic correlations in CrSBr.
• To understand the behavior of these correlations in relation to temperature and dimensionality.
• To explore the potential for frustrated phases in CrSBr.

Main Methods:

• Small-angle neutron scattering (SANS) was employed to probe magnetic correlations.
• Analysis using an effective spin Hamiltonian to model experimental results.

Main Results:

• Short-range magnetic regions in CrSBr show increasing correlation lengths upon cooling, reaching ~3 nm at the antiferromagnetic ordering temperature (T_N ≈ 140 K).
• Ferromagnetic correlations develop below 200 K, well above T_N, and diminish rapidly below T_N.
• These correlations are intrinsic to the monolayer limit and rule out a frustrated phase at low temperatures within the experimental window (2-200 nm).

Conclusions:

• The findings support a spin freezing scenario for magnetic fluctuations in CrSBr.
• Small-angle neutron scattering is a valuable technique for studying phenomena beyond long-range order in van der Waals magnets.
• Short-range correlations are a key intrinsic property of 2D CrSBr.