Spontaneous Fully Compensated Ferrimagnetism

TL;DR

This paper introduces a general mechanism for spontaneous fully compensated ferrimagnetism (fFIM), revealing its electronic, optical, and material properties, and proposes its realization in graphene through defect engineering, with implications for spintronics and valleytronics.

Contribution

It provides a unified theoretical framework for understanding, predicting, and realizing spontaneous fFIM in materials, including graphene, with detailed analysis of its properties and potential applications.

Findings

Spontaneous fFIM exhibits zero net magnetization with ferromagnetic-like band structures.

Optical selection rules and valley- and spin-related physics are governed by quantum geometry.

Spontaneous fFIM can be engineered in graphene via defect manipulation.

Abstract

We propose a general mechanism for the spontaneous emergence of filling-enforced fully compensated ferrimagnetism (fFIM), characterized by zero net magnetization yet ferromagnetic-like spin-split band structures. Using Hartree-Fock mean-field calculations of the Hubbard model, we map out the stability regime of spontaneous fFIM over a broad parameter space of interaction strength and staggered potential. We show the unique quantum-geometry-governed optical selection rules and the abundant valley- and spin-related physics of electronics and optics arising from the emergence of fFIM order, with tunable spin-polarized and valley-contrasting charge and spin currents. Furthermore, based on our theory, we demonstrate that spontaneous fFIM can be realized in nominally nonmagnetic graphene via defect engineering. Our results establish a unified framework for the mechanism, emergent properties, and materials realization of spontaneous fFIM, opening new opportunities for spintronic, valleytronic, and optoelectronic applications.