Permanent Electride Magnets Induced by Quasi-Atomic Non-Nucleus-Bound Electrons

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Interstitial quasi-atomic electrons (IQEs) possess magnetic moments and influence magnetism in crystalline electrides.
• Achieving large magnetic anisotropy for hard magnetism in electrides is challenging due to weak spin-orbit coupling and exchange interactions involving IQEs.

Purpose of the Study:

• To investigate the origin of permanent magnetism and large magnetocrystalline anisotropy in novel 2D electrides.
• To explore the role of the IQE magnetic sublattice in driving hard magnetic properties.

Main Methods:

• Synthesis and characterization of 2D [Re2C]2+·2e− electrides (Re = Er, Ho, Dy, Tb).
• Magnetic property measurements including coercivity and energy product.
• Investigating magnetic interactions between rare-earth (Re) and IQE sublattices.

Main Results:

• 2D [Re2C]2+·2e− electrides exhibit permanent magnetism in a ferrimagnetic state.
• Significant magnetocrystalline anisotropy and high coercivity (up to 15 MGOe) were observed.
• Substitution with paramagnetic elements broke the IQE sublattice, leading to antiferromagnetic ordering of the Re sublattice, confirming IQE-driven magnetism.

Conclusions:

• The magnetic sublattice of IQEs is the primary driver of permanent magnetism in these 2D electrides.
• These findings open pathways for designing new hard magnetic materials based on electrides.
• The controlled manipulation of the IQE sublattice offers a strategy to tune magnetic properties.