Visualizing Atomically Layered Magnetism in CrSBr

Abstract

ability to synthesize and characterize 2D materials with long-range magnetic order was notably absent. Such materials hold great promise for potential applications in spintronics, [6][7][8][9][10][11] topological superconductivity, [12,13] vdW heterostructures, [14,15] and memory storage. [16,17] Hypothetical 2D magnets defy the Mermin-Wagner theorem, [18] which states that long-range magnetic order cannot exist at finite temperature within the 2D isotropic Heisenberg model. [19] Hence, magnetic anisotropy is a necessary prerequisite to realizing stable 2D magnetism, and has been demonstrated to exist in several layered materials over the last few years. [3,4,[20][21][22][23][24][25][26] Among these, the chromium trihalides CrX 3 (X = Cl, Br, I) have been the most extensively studied, all of which display intralayer ferromagnetic (FM) order and either FM or antiferromagnetic (AFM) interlayer coupling depending on the choice of halide and crystal thickness. [27] Despite their extensive characterization, chromium trihalides suffer from a lack of air and moisture stability and possess relatively low transition temperatures, limiting their applications. On the other hand, CrSBr has emerged [28][29][30][31] as an air-stable layered magnetic material possessing A-type AFM ordering with a comparatively high Néel temperature (T N ≈ 132 K).A variety of analytical tools have been used to characterize CrSBr, including magnetometry, [32,33] magneto-transport, [32,33] 2D materials can host long-range magnetic order in the presence of underlying magnetic anisotropy. The ability to realize the full potential of 2D magnets necessitates systematic investigation of the role of individual atomic layers and nanoscale inhomogeneity (i.e., strain) on the emergence of stable magnetic phases. Here, spatially dependent magnetism in few-layer CrSBr is revealed using magnetic force microscopy (MFM) and Monte Carlo-based simulations. Nanoscale visualization of the magnetic sheet susceptibility is extracted from MFM data and force-distance curves, revealing a characteristic onset of both intra-and interlayer magnetic correlations as a function of temperature and layer-thickness. These results demonstrate that the presence of a single uncompensated layer in odd-layer terraces significantly reduces the stability of the low-temperature antiferromagnetic (AFM) phase and gives rise to multiple coexisting magnetic ground states at temperatures close to the bulk Néel temperature (T N ). Furthermore, the AFM phase can be reliably suppressed using modest fields (≈16 mT) from the MFM probe, behaving as a nanoscale magnetic switch. This prototypical study of few-layer CrSBr demonstrates the critical role of layer parity on field-tunable 2D magnetism and validates MFM for use in nanomagnetometry of 2D materials (despite the ubiquitous absence of bulk zero-field magnetism in magnetized sheets).The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202201000.

Magnon Straintronics in the 2D van der Waals Ferromagnet CrSBr from First-Principles

“…S and Br atoms are slightly spin polarized with −0.27 μ B and −0.08 μ B , respectively. The most stable magnetic configuration is achieved for FM ordering with in-plane magnetization along the b axis (Figure b), in agreement with experiments. − …”

Unexpected Piezoresistive Effect, Room‐Temperature Ferromagnetism, and Thermal Stability of 2D β‐CuI Crystals in Reduced Graphene Oxide Membrane

“…2D materials exhibit many peculiar properties due to the confinement of carrier migration and heat diffusion in 2D planes, [1] which have shown potential in electric, [2] magnetic, [3,4] optical, [5] chemical, and biomedical applications. [6,7] Studying the synthesis of novel 2D materials and exploring their new physical and chemical properties in the 2D limit are essential both for new potentials and for understanding the origin of their promising properties.…”

Local Fluctuations in Cavity Control of Ferroelectricity

“…In the future it would be extremely interesting to extend this approach to include more complex heterostructures which feature multiple types material [65,66] including metals [67], insulators [68], superconductors [69,70], ferroelectrics [41][42][43][44][45], magnets [71][72][73][74][75][76][77], and multiferroics [78]-all of which are phases of matter which can be characterized by their couplings to electromagnetic fields and which are now realizeable down to the twodimensional limit [79]. In the future it would be very interesting to consider the mutual coupling of different stacked phases through their shared quantum electrodynamic environment.…”