Study of Magnetoresistance Plateau as a Probe of Spin‐Wave Excitations in Fe4$_4$GeTe2$_2$

Magnetic anisotropy is a key factor in stabilizing magnetic long‐range order in 2D van der Waals (vdW) ferromagnets, circumventing the limitations of low‐dimensional magnetism as described by the Mermin–Wagner theorem. FeGeTe (F4GT) is a nearly room‐temperature ferromagnet, well known for hosting competing anisotropic interactions that lead to a spin‐reorientation transition. In this report, we analyze the nature of magnetic anisotropy and spin‐wave excitation in F4GT through a comprehensive study of its magnetic and magneto‐transport properties. Our findings reveal the novel observation of a spin‐wave excitation gap, giving rise to magnetoresistance plateaus in F4GT.