Chemically Functionalized Phosphorene: Two-Dimensional Multiferroics with Vertical Polarization and Mobile Magnetism

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Ideal nonvolatile memories (NVMs) require 2D multiferroic materials for efficient ferroelectric writing and ferromagnetic reading.
• Such materials combining both properties have not been previously reported.

Purpose of the Study:

• To provide first-principles evidence for a novel 2D multiferroic material.
• To explore its potential for advanced NVM applications.

Main Methods:

• First-principles calculations were used to investigate the properties of a halogen-intercalated phosphorene bilayer.
• The study focused on controlling magnetism via ferroelectric switching using an external electric field.

Main Results:

• A halogen-intercalated phosphorene bilayer exhibits multiferroic properties.
• Magnetism is controllable by ferroelectric switching, enabling "on" (spin-selective, p-doped) and "off" (insulating) states.
• Vertical polarization is robust against depolarizing fields, allowing high-density data storage.
• Each intercalated adatom can store one bit of data, suggesting single-atom memory potential.

Conclusions:

• Halogen-intercalated phosphorene bilayers are promising candidates for future 2D multiferroic NVMs.
• The unique properties of covalently bonded ferroelectrics offer advantages over ionic-bonded ones.
• This approach may be extendable to other van der Waals bilayers for NVM design.