Description
The development of high-performance van der Waals (vdW) magnets is often hindered by a fundamental dichotomy: localized $3d$ states provide robust magnetism but suffer from weak exchange and minor (or even negligible) spin-orbit coupling (SOC), while heavy $5p$ states offer massive SOC but lack intrinsic magnetic order. In this work, we demonstrate that a negative charge-transfer (NCT) magnet resolves this conflict, as exemplied by MnSiTe$_3$, using first-principles calculations and physical pictures.
We reveal that the high-temperature ferromagnetism is driven by the spontaneous self-doped itinerant Te 5$p$ ligand holes, which significantly amplify magnetic exchange interactions beyond the limits of conventional superexchange and yield strong magnetic anisotropy. Moreover, we find that the active participation of these $5p$ ligand holes, rather than acting as a passive background, generates a dense manifold of Weyl nodes around the Fermi level. This results in a remarkable anomalous Hall effect in a broad energy range. We further propose a room-temperature three-level spintronic device controlled by an easy in-plane magnetization rotation. Our work establishes the NCT mechanism as a superior paradigm for synthesizing $3d$-$5p$ vdW magnets that simultaneously possess record-high $T_{\rm C}$, strong SOC, and robust topological transport.
