Understanding Antiferromagnetic Coupling in Lead-Free Halide Double Perovskite Semiconductors

Area of Science:

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

Background:

• Solution-processable semiconductors with antiferromagnetic order are crucial for advanced spintronics and data storage.
• Halide perovskites containing magnetic ions show promise as multifunctional materials linking structural, optical, electrical, and magnetic properties.
• Stable antiferromagnetic optoelectronic halide perovskites are scarce, necessitating development of design rules for magnetic coupling.

Purpose of the Study:

• Investigate antiferromagnetic coupling in stable Cs ₂ (Ag:Na)FeCl ₆ semiconductor alloys.
• Determine the role of nonmagnetic monovalence ions at the B ^I site in facilitating magnetic interactions.
• Establish design principles for optimizing antiferromagnetic halide double perovskites.

Main Methods:

• Hydrothermal synthesis of Cs ₂ (Ag:Na)FeCl ₆ bulk semiconductor alloys.
• Complementary magnetometry and electron-spin-resonance experiments.
• First-principles calculations to elucidate magnetic coupling mechanisms.

Main Results:

• Demonstrated the importance of Na/Ag at the B ^{I} site for superexchange interaction via orbital hybridization.}
• Achieved tunable Curie-Weiss parameters ranging from -27 to -210 K.
• Showcased potential for promoting magnetic frustration through alloying at the nonmagnetic B ^{I} site.}

Conclusions:

• Nonmagnetic ion substitution at the B ^{I} site is key for optimizing antiferromagnetic coupling in halide double perovskites.}
• The study provides a cohesive picture for designing B-site-ordered antiferromagnetic halide double perovskites.
• Findings pave the way for novel spintronic and information storage applications.