Metal-insulator Crossover Behavior at the Surface of NiS_2

Abstract

We have performed a detailed high-resolution electron spectroscopic investigation of NiS${}_2$ and related Se-substituted compounds NiS${}_{2-x}$Se${}_x$, which are known to be gapped insulators in the bulk at all temperatures. A large spectral weight at the Fermi energy of the room temperature spectrum, in conjunction with the extreme surface sensitivity of the experimental probe, however, suggests that the surface layer is metallic at 300 K. Interestingly, the evolution of the spectral function with decreasing temperature is characterized by a continuous depletion of the single-particle spectral weight at the Fermi energy and the development of a gap-like structure below a characteristic temperature, providing evidence for a metal-insulator crossover behavior at the surfaces of NiS${}_2$ and of related compounds. These results provide a consistent description of the unusual transport properties observed in these systems.

12 pages, 3 figures

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Cited by in corpus (6)

• Electric Field Effect in Diluted Magnetic Insulator Anatase Co:TiO2
• Direct observation of the bandwidth control Mott transition in the NiS${}_{2-x}$Se${}_x$ multiband system
• X-ray photoemission study of NiS_{2-x}Se_x (x = 0.0 - 1.2)
• Atomic Diffusion in the Surface State of Mott Insulator NiS2
• Metallic surface of a bipolaronic insulator
• Closing of the Mott gap near step edges in NiS2