Van der Waals Epitaxy Growth of 2D Single-Element Room-Temperature Ferromagnet

The evolution of chemical ordering and property in Fe1+x Se2 upon intercalation ratios

Intercalation has been considered as an effective method to explore innovative two-dimensional (2D) materials and modify their properties. However, the relationship between intercalation concentration, structure, and property remains a largely uncharted territory, and the controllable synthesis of desired intercalated phases faces challenges. Here, a general intercalated rule for the effect of self-intercalation ratio on atomic arrangements is revealed. Then, the controllable synthesis of a series of Fe-intercalated 2D materials is realized. Scanning transmission electron microscopy illustrates that their intercalation structures undergo disordered/ordered/half-ordered/ordered transformation, which confirms the intercalated rule and proposes a new structure termed half-ordered intercalation. Notably, their magnetic and electrical properties can be significantly modulated by intercalation. Orderly intercalated nanoflakes possess room-temperature magnetism with composition-regulated magnetic domains. Moreover, Fe1.5Se2 and Fe1.6Se2 are scarce half-metallic materials showing different magneto-resistance behaviors. This work would guide the design and synthesis of new intercalated materials, and deepen the understanding of the relationship between structure and properties.

2D Ferroic Materials for Nonvolatile Memory Applications

The emerging nonvolatile memory technologies based on ferroic materials are promising for producing high-speed, low-power, and high-density memory in the field of integrated circuits. Long-range ferroic orders observed in 2D materials have triggered extensive research interest in 2D magnets, 2D ferroelectrics, 2D multiferroics, and their device applications. Devices based on 2D ferroic materials and heterostructures with an atomically smooth interface and ultrathin thickness have exhibited impressive properties and significant potential for developing advanced nonvolatile memory. In this context, a systematic review of emergent 2D ferroic materials is conducted here, emphasizing their recent research on nonvolatile memory applications, with a view to proposing brighter prospects for 2D magnetic materials, 2D ferroelectric materials, 2D multiferroic materials, and their relevant devices.