A prototypical charge-transfer type Mott insulator NiS2 pyrite exhibits a metal-insulator transition with bandwidth control. Recent discoveries on surface-specific electronic states on other 3d transition-metal disulfide pyrites motivate us to further investigate the surface of NiS2, where metallic surface conduction is discussed. Here, the spectroscopic-imaging scanning-tunneling-microscopy observations revealed that the surface is not metallic, contrary to the expectation. Instead, the Mott gap is closed near step edges, suggesting possible electrical conduction from one-dimensional channels. The edge anomaly was observed irrespective of its magnetic order and is limited to the insulator phases.
@article{arxiv.2407.19636,
title = {Closing of the Mott gap near step edges in NiS2},
author = {Yuuki Yasui and Kota Iwata and Shota Okazaki and Shigeki Miyasaka and Yoshiaki Sugimoto and Tetsuo Hanaguri and Hidenori Takagi and Takao Sasagawa},
journal= {arXiv preprint arXiv:2407.19636},
year = {2024}
}