Intrinsic Altermagnetic-Ferroelectric Multiferroicity and Magnetoelectric Coupling in Reversed Transition-Metal...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid State Chemistry

Background:

• Multiferroic materials integrate magnetic and ferroelectric orders, enabling novel physical phenomena.
• Recent proposals suggest combining van der Waals altermagnetism with sliding ferroelectricity in single crystals.
• Investigating diverse magnetoelectric couplings and their mechanisms is crucial for advancing multiferroic research.

Purpose of the Study:

• To identify materials exhibiting both robust altermagnetism and sliding ferroelectricity.
• To explore interlayer engineering and symmetry constraints for novel multiferroic functionalities.
• To establish a paradigm for developing advanced multiferroics in transition metal bromides.

Main Methods:

• First-principles calculations to guide material selection and understand electronic properties.
• Spin space group analysis to determine magnetic symmetries and their interplay with ferroelectricity.
• Targeted interlayer engineering to tune material properties and achieve desired coupled orders.

Main Results:

• NiBr2 and MnBr2 were identified as materials simultaneously hosting robust altermagnetism and sliding ferroelectricity.
• MnBr2 exhibits spontaneous locking of altermagnetism to the ferroelectric state at maximal polarization.
• Deterministic magnetoelectric coupling and nonvolatile electric control of magnetization were achieved in MnBr2.

Conclusions:

• This study presents the first material realization of coupled altermagnetism and sliding ferroelectricity.
• A generic symmetry-engineering paradigm for developing advanced multiferroics was established.
• Transition metal bromides offer a promising platform for future multiferroic material discovery.