Revealing the Role of the Tetragonal Distortion in the Metal-Insulator Transition of Co- and Fe-Doped NiS.

Although the NiS exhibits the most widely adjustable metal-to-insulator (MIT) properties among the chalcogenides, the mechanisms, with respect to the regulations in their critical temperatures (), are yet unclear. Herein, we demonstrate the overlooked role associated with the structurally tetragonal distortion in elevating the of NiS; this is in distinct contrast to the previously expected hybridization and bandwidth regulations that usually reduces . Compared to the perspective of structure distortions, the orbital hybridization and band regulation of NiS are ∼19 times more effective adjustment in .