Thickness-dependent topological spin texture nucleation in the high-temperature two-dimensional ferromagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msub> <mml:mi>Fe</mml:mi> <mml:mn>3</mml:mn> </mml:msub> <mml:msub>

<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:msub> <a:mi>Fe</a:mi> <a:mn>3</a:mn> </a:msub> <a:msub> <a:mi>GaTe</a:mi> <a:mn>2</a:mn> </a:msub> </a:mrow> </a:math> (FGaT) has emerged as a promising two-dimensional (2D) ferromagnet with intrinsic magnetism above room temperature. Here, we investigate the thickness-dependent nucleation and stability of topological spin textures in exfoliated FGaT flakes with thicknesses ranging from 45 to <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"> <b:mrow> <b:mn>290</b:mn> <b:mspace width="4pt"/> <b:mi>nm</b:mi> </b:mrow> </b:math> using scanning transmission x-ray microscopy. The domain size exhibits a nonmonotonic dependence on thickness, deviating from classical Kittel's <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"> <d:msup> <d:mi>t</d:mi> <d:mrow> <d:mn>1</d:mn> <d:mo>/</d:mo> <d:mn>2</d:mn> </d:mrow> </d:msup> </d:math> scaling due to enhanced domain-wall energy in thinner samples. Magnetic phase diagrams indicate that skyrmion nucleation becomes increasingly favorable with thickness, with a significantly expanded stability region in thicker flakes. In contrast, high-order spin textures are suppressed below <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mo>∼</e:mo> <e:mn>75</e:mn> <e:mspace width="4pt"/> <e:mi>nm</e:mi> </e:mrow> </e:math> , highlighting a critical limitation for the miniaturization of 2D skyrmion-based spintronic devices. Our results emphasize the need for better stabilization strategies, such as interfacial engineering in van der Waals heterostructures, to enable robust topological textures in thin 2D magnet flakes.