Structure–property correlations in magnetic two-dimensional intercalation compounds

Recently discovered two-dimensional (2D) magnetic materials are promising candidates for energy-efficient electronics because their atomically thin nature makes them highly responsive to low-energy external stimuli. However, realizing the promise of these materials for ultralow-power electronic devices, requires a new design framework for 2D magnets in which the spin–spin interactions can be precisely tailored by modulating the spatial distribution of spin-bearing atoms/ions. Here, we present structure–property relations in 2D Fe_xTaS₂ (x ≤ 0.5), a novel low-dimensional magnetic material, which exhibits hard ferromagnetic behavior down to the thinnest limit (Fe-intercalated bilayer TaS₂), with large coercive fields of ~3 T. We systematically alter the distribution and symmetry of spin-bearing ions in 2D Fe_xTaS₂ by chemically intercalating Fe²⁺ centers into few-layer TaS₂, a host lattice with no long-range magnetic ordering. We examine the behavior of these 2D magnetic materials using variable-temperature quantum transport, transmission electron microscopy, and optical (Raman, synchrotron X-ray) measurements. These analyses shed new light on the coupled effects of intercalation amount, symmetry, order/disorder, and dimensionality on the magnetic behavior of 2D Fe_xTaS₂. More broadly, our intercalation approach to 2D magnets introduces a versatile phase space of low-dimensional magnets, in which magnetic properties can be tuned by the choice of the host material and intercalant identity/amount, in addition to the manifold degrees of freedom available to other atomically thin materials.