Hard ferromagnetism down to the thinnest limit of iron-intercalated\n tantalum disulfide

Two-dimensional (2D) magnetic crystals hold promise for miniaturized and\nultralow power electronic devices that exploit spin manipulation. In these\nmaterials, large, controllable magnetocrystalline anisotropy is a prerequisite\nfor the stabilization and manipulation of long-range magnetic order. In known\n2D magnetic crystals, relatively weak magnetocrystalline anisotropy results in\ntypically soft ferromagnetism. Here, we demonstrate that ferromagnetic order\npersists down to the thinnest limit of Fe$_x$TaS$_2$ (Fe-intercalated bilayer\n2H-TaS$_2$) with giant coercivities up to 3 tesla. We prepare Fe-intercalated\nTaS$_2$ by chemical intercalation of van der Waals layered 2H-TaS$_2$ crystals\nand perform variable-temperature quantum transport, transmission electron\nmicroscopy, and confocal Raman spectroscopy measurements to shed new light on\nthe coupled effects of dimensionality, degree of intercalation, and intercalant\norder/disorder on the hard ferromagnetic behavior of Fe$_x$TaS$_2$. More\ngenerally, we show that chemical intercalation gives access to a rich synthetic\nparameter space for low-dimensional magnets, in which magnetic properties can\nbe tailored by the choice of the host material and intercalant identity/amount,\nin addition to the manifold distinctive degrees of freedom available in\natomically thin, van der Waals crystals.\n