Year: 2026
Type: preprint
Abstract: Understanding the evolution of magnetic order in the two-dimensional limit remains a central challenge in van der Waals magnets, where thermodynamic measurements are constrained by the femtogram-scale mass of exfoliated flakes. Here, microsecond pulse-heating nanocalorimetry is used to measure the heat capacity and magnetic entropy of CrSBr flakes down to the monolayer limit. The measurements reveal the entropy landscape associated with magnetic ordering, uncovering a decreasing interlayer transition temperature toward the monolayer limit and an entropy-derived effective moment per layer that increases with thickness toward the expected spin-only scale. Thermodynamic anomalies capture a crossover from bulk-like interlayer antiferromagnetism to a regime dominated by intralayer ferromagnetic correlations. A pronounced layer-parity effect further emerges, with odd-layer samples displaying an additional high-temperature contribution associated with uncompensated magnetic layers. Under in-plane magnetic fields applied along the easy axis, antiferromagnetic order is progressively suppressed, allowing extraction of a thickness-dependent characteristic suppression field reflecting weakened interlayer exchange coupling. Entropy analysis further reveals an extended regime of magnetic fluctuations persisting well above the interlayer ordering transition. Together, these results establish nanocalorimetry as a powerful thermodynamic probe of low-dimensional magnetism, providing direct access to magnetic entropy, exchange interactions, and dimensional crossover in atomically thin van der Waals magnets.
Source: arXiv (Cornell University)
Institutions: Universitat Autònoma de Barcelona, Institut Català de Nanociència i Nanotecnologia, UCLouvain, Consejo Superior de Investigaciones Científicas, Centro Nacional de Microelectrónica, Institut de Microelectrònica de Barcelona, Columbia University, National Institute for Materials Science, Research Center for Materials Nanoarchitectonics
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: Ministerio de Ciencia, Innovación y Universidades, Centres de Recerca de Catalunya, Institut Català de Nanociència i Nanotecnologia, Ministry of Education, Culture, Sports, Science and Technology, Fonds De La Recherche Scientifique - FNRS, Generalitat de Catalunya, Ministerio de Ciencia e Innovación, Multidisciplinary University Research Initiative, Core Research for Evolutional Science and Technology, Air Force Office of Scientific Research
Awards: G1206670709, G1523888516, G1580565680, G1610934229, G2051183867, G2326233582, G2438242660, G2474288685, G2474572798, G2640929160, G3475565437, G4091144171, G4135464282, G4839010319, G5271842468, G5357804864, G5706383408, G6011688299, G6605876378, G6762955466, G6824056442, G7033518186, G708600390
OpenAlex ID: W7172251227