Nonmagnetic ground state of marcasite FeTe${}_2$: The competition between crystal field splitting and on-site Coulomb repulsion

Abstract

The magnetic ground states in crystalline systems are significant for both fundamental condensed matter physics and practical materials engineering. Marcasite FeTe${}_2$, characterized as a small-gap semiconductor, exhibits anomalous magnetic behaviors in low-temperature experiments. In this study, first-principles density functional theory calculations combined with scanning tunneling microscopy/spectroscopy are employed to investigate the magnetic ground state of marcasite FeTe${}_2$. It is revealed that the competition between crystal field splitting and on-site Coulomb repulsion plays the key role in the formation of localized magnetic moments in FeTe${}_2$. The ground state of FeTe${}_2$ bulk is confirmed to be nonmagnetic, while the magnetic responses of FeTe${}_2$ observed at low temperature are suggested to be related to the magnetic Fe atoms on the crystal surfaces. Our work proposes a straightforward competing mechanism for determining ground-state magnetism of various localized-moment crystalline systems.

5 figures, 10 pages. Some revisions were performed. Comments are welcome