The discoveries of ferromagnetic and ferroelectric two-dimensional (2D) materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories. This review focuses on the latest 2D ferromagnetic and ferroelectric materials that have been most recently studied, including insulating ferromagnetic, metallic ferromagnetic, antiferromagnetic and ferroelectric 2D materials. The fundamental properties that lead to the long-range magnetic orders of 2D materials are discussed. The low Curie temperature (T_c) and instability in 2D systems limits their use in practical applications, and several strategies to address this constraint are proposed, such as gating and composition stoichiometry. A van der Waals (vdW) heterostructure comprising 2D ferromagnetic and ferroelectric materials will open a door to exploring exotic physical phenomena and achieve multifunctional or nonvolatile devices.

The electron–hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots (Cdots) is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp² clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π–π^* states of the sp² domains decreases as the sp² cluster size increases. More importantly, the strong electron–hole exchange interaction results in the splitting of the exciton states of the sp² clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp² cluster size owing to the reduction of the confinement energy and the suppression of the electron–hole exchange interaction.