Layer- and Field-Dependent Magnetic Order in 2D CrSBr Revealed by Pulsed Nanocalorimetry

We report the first direct determination of the heat capacity (Cp) of few-layer CrSBr, a layered van der Waals antiferromagnet, using a microsecond-pulsed nanocalorimetry technique with sub-picojoule sensitivity. The onset of magnetic order in CrSBr is reflected in Cp(T) through a distinct anomaly associated with the magnetic entropy change at the Néel transition. This approach enables quantitative calorimetric measurements on encapsulated flakes down to a few atomic layers, providing direct thermodynamic access to the antiferromagnetic transition in the 2D limit.

The Cp(T) curves reveal a pronounced anomaly around 132 K, whose amplitude and sharpness systematically evolve with layer thickness, from monolayer to bulk CrSBr, revealing how the magnetic order develops with dimensionality. The technique also enables in-situ calorimetry under applied in-plane magnetic fields, showing that the antiferromagnetic transition is reversibly suppressed above a critical field that strongly depends on the number of layers, increasing progressively from few-layer to bulk-like samples.

These results establish microsecond-pulsed nanocalorimetry as a powerful platform to probe emergent magnetism and spin–lattice coupling in 2D materials, providing unprecedented thermodynamic insight into the dimensional evolution of magnetic order in van der Waals systems.