Orbital mixing as key ingredient for magnetic order in a van der Waals ferromagnet

TL;DR

This study uncovers how orbital mixing between iodine p orbitals and chromium eg states stabilizes ferromagnetism in the 2D van der Waals magnet CrI3, linking electronic structure to magnetic order.

Contribution

It provides the first detailed experimental and theoretical analysis of the orbital mechanisms underlying ferromagnetism in CrI3, highlighting the role of orbital mixing.

Findings

Orbital mixing between I p and Cr eg states stabilizes ferromagnetism.

Electronic structure analysis reveals differences between paramagnetic and ferromagnetic phases.

Experimental and DFT results confirm the microscopic origin of magnetic order.

Abstract

Recent years have seen a vast increase in research into van der Waals magnetic materials. In many of these systems, magnetism is introduced via light 3\textit{d}-transition metal elements, combined with chalcogenides or halogens. Despite the high technological promise in the field of spintronics, the connection between the \textit{d}-orbital configuration and the occurrence of low-dimensional magnetic order is currently unclear. Here we address the prototypical two-dimensional ferromagnet CrI\textsubscript{3}, via complementary spectroscopies and density functional theory calculations. We reveal the electronic structure and orbital character of bulk CrI\textsubscript{3} in the paramagnetic and ferromagnetic phases, describing the couplings underpinning its energy diagram, and providing a robust experimental demonstration that the mechanism of stabilization of ferromagnetism is attributable to orbital mixing between I \textit{p} and Cr \textit{e\textsubscript{g}} states. These findings reveal the microscopic connection between orbital and spin degrees of freedom, providing fundamental insights into the behavior of low-dimensional magnetic materials.