Advancing Room-Temperature Magnetic Semiconductors with Organic Radical Charge Transfer Cocrystals

Area of Science:

• Materials Science
• Organic Electronics
• Spintronics

Background:

• Developing purely organic room-temperature magnetic semiconductors is crucial for controlling spin and charge simultaneously.
• Organic cocrystals offer structural versatility for magnetoelectric coupling applications, but their magnetic semiconductor properties are poorly understood.
• Doping organic cocrystals with radicals presents a viable strategy to enhance magnetism and conductivity while preserving cocrystal structures.

Purpose of the Study:

• To construct and characterize a novel organic room-temperature magnetic semiconductor cocrystal.
• To investigate the mechanism behind enhanced ferromagnetism and conductivity in radical-doped cocrystals.
• To demonstrate room-temperature magnetoelectric coupling in the developed material.

Main Methods:

• Fabrication of fluoranthene-7,7,8,8-tetracyanoquinodimethane radical (FA-HTCNQ•) cocrystals using a solution-processing approach.
• Characterization of magnetic properties, including coercive fields and Curie temperature.
• Evaluation of electrical conductivity and demonstration of room-temperature magnetoelectric coupling.

Main Results:

• The conductive FA-HTCNQ• cocrystal exhibits excellent room-temperature ferromagnetism with a Curie temperature near 400 K and coercive fields of 96 Oe.
• Superior magnetic and conductive properties were observed compared to the undoped counterpart.
• Room-temperature magnetoelectric coupling was successfully demonstrated in the FA-HTCNQ• material.

Conclusions:

• Enhanced ferromagnetism and conductivity in organic cocrystals are attributed to radical-induced charge-transfer interactions.
• The study elucidates the origin of ferromagnetism in organic cocrystals.
• A simple strategy for fabricating pure organic room-temperature magnetic semiconductors for integrated magnetoelectric devices is provided.