Controlled synthesis and excellent magnetism of ferrimagnetic NiFe2Se4 nanostructures

3d transition metal chalcogenides have attracted much attention due to their unique magnetic properties. Although various Cr, V, and Fe-based chalcogenides have been fabricated recently, the limited Curie temperature (TC) still hinders their practical application. Based on the structural and magnetic advantages of MFe2O4 and Fe3Se4, we developed a one-pot solution synthesis method for the fabrication of NiFe2Se4 nanostructures with structural continuity, to facilitate the investigation of their magnetic properties. Notably, the morphology of NiFe2Se4 can be controlled from nano-rods to nano-platelets by controlling the growth direction. The coercivity (HC) of NiFe2Se4 with nano-cactus structure exhibits a maximum of 12.77 kOe at 5 K. The coercivity of ferrimagnetic NiFe2Se4 nano-platelets can be further adjusted to 1.52 kOe at room temperature. These results show that the magnetic properties of NiFe2Se4 can be significantly modified by controlling their morphologies. We also extend the method to the synthesis of CoFe2Se4 nano-cactus with an ultrahigh coercivity of 17.85 kOe at 5 K. Obviously, the synthesis strategy and their excellent magnetic properties of MFe2Se4 have sparked interest in ternary transition metal selenides as potential hard magnetic materials.