Ferromagnetic Negative Charge-Transfer Insulator: from Theoretical Proposal to Material Realization

Abstract

Here we propose another type of ferromagnetic semiconductors: ferromagnetic negative charge-transfer insulator (FNCTI). In FNCTI, the negative charge-transfer states strongly enhance the ferromagnetic (FM) exchange interactions and the orbital hybridization gap permits the magnetic molecular orbitals as the underlying magnetic units rather than local atomic orbitals. Thus the FM exchange interactions are rather strong and decay slowly due to the large spearding of magnetic molecular orbitals. This is distinct from the superexchange mechanism where FM exchange interactions are quite weak as summarized in the well-known Goodenough-Kanamori-Anderson semi-empirical rules.Through first-principle calculations with the hybrid functional, PbO-type CrAs monolayer is mapped out to be a FNCTI, which possesses a band gap $\sim$ 0.35 eV, FM nearest-/next-nearest-neighbor exchange coupling strength $\sim$ 57/40 meV, and a high $T_c$ $\sim$ 1500 K respectively. It is believed that the existence of FNCTI validates the long-pending hypothesis by D. I. Khomskii and G. A. Sawatzky in 1997 [Solid State Commun. 102, 87 (1997)].

25 pages, 13 figures, a huge extension version

References in corpus (7)

• Hubbard U and Hund's Exchange J in Transition Metal Oxides: Screening vs. Localization Trends from Constrained Random Phase Approximation
• Ground state oxygen holes and the metal-insulator transition in the negative charge transfer rare-earth nickelates
• Screened Coulomb interaction in the maximally localized Wannier basis
• Superconductivity in the vicinity of antiferromagnetic order in CrAs
• Quantum anomalous Hall effect from inverted charge transfer gap
• Mean-field solution of the Hubbard model: the magnetic phase diagram
• Room-temperature ferromagnetism at an oxide/nitride interface

Cited by in corpus (2)

• Generic Approach to Intrinsic Magnetic Second-order Topological Insulators via Inverted $p-d$ Orbitals
• Enhanced Itinerant Ferromagnetism in Hole-doped Transition Metal Oxides: Beyond the Canonical Double Exchange Mechanism