Free-standing 2D ironene with magnetic vortex structure at room temperature

Abstract

•Te promoter and space-confined setup are two key factors for synthesizing 2D ironene •2D ironene nanoflakes exhibit intrinsic ferromagnetism at room temperature •Thickness and geometrical shape-dependent magnetic vortex structures are demonstrated •Magnetic domain evolution and domain wall motion are observed in situ Free-standing two-dimensional (2D) elemental transition metal single crystals are an important kind of nanomaterial, with abundant fascinating theoretical properties, such as magnetism. To date, however, they rarely have been grown and studied because of the difficulty in controllable synthesis, since the existence of surface dangling bonds makes the 2D growth of these crystals challenging. Herein, we discuss developing a Te-assisted chemical vapor deposition (CVD) method and growing 2D Fe single-crystal nanoflakes (termed ironene) with different thicknesses, illustrating that Te powder and space-confined setup are the two key factors. Notably, thickness and geometrical shape-dependent magnetic domain structure of the obtained 2D ironene at room temperature was explored. Furthermore, this interesting domain configuration was confirmed by Lorentz transmission electron microscopy (LTEM), and magnetic domain manipulation was performed in situ. This work provides a valuable case study for synthesizing 2D elemental transition metal nanoflakes with room-temperature ferromagnetism and paves the way for developing new diverse spintronics. Free-standing two-dimensional (2D) elemental transition metal single crystals are an important kind of nanomaterial, with abundant fascinating theoretical properties, such as magnetism. To date, however, they rarely have been grown and studied because of the difficulty in controllable synthesis, since the existence of surface dangling bonds makes the 2D growth of these crystals challenging. Herein, we discuss developing a Te-assisted chemical vapor deposition (CVD) method and growing 2D Fe single-crystal nanoflakes (termed ironene) with different thicknesses, illustrating that Te powder and space-confined setup are the two key factors. Notably, thickness and geometrical shape-dependent magnetic domain structure of the obtained 2D ironene at room temperature was explored. Furthermore, this interesting domain configuration was confirmed by Lorentz transmission electron microscopy (LTEM), and magnetic domain manipulation was performed in situ. This work provides a valuable case study for synthesizing 2D elemental transition metal nanoflakes with room-temperature ferromagnetism and paves the way for developing new diverse spintronics.