Magnetic ordering through itinerant ferromagnetism in a metal-organic framework
Jesse G Park1, Brianna A Collins2, Lucy E Darago1
1Department of Chemistry, University of California, Berkeley, CA, USA.
Nature Chemistry
|April 16, 2021
Summary
Researchers achieved the highest ferromagnetic ordering temperature yet in a metal-organic framework, reaching 225 K. This breakthrough utilizes itinerant ferromagnetism for potential spintronics and magnetoelectric applications.
Area of Science:
- Materials Science
- Solid-State Physics
- Chemistry
Background:
- Multifunctional magnetic materials are crucial for spintronics, quantum sensing, and gas separations.
- Metal-organic frameworks (MOFs) offer tunable properties but typically exhibit magnetic order only at low temperatures due to weak magnetic exchange.
- Achieving higher magnetic ordering temperatures in MOFs is a significant challenge.
Purpose of the Study:
- To realize magnetic ordering at an elevated temperature in a metal-organic framework.
- To investigate the mechanism of itinerant ferromagnetism in a novel chromium-based MOF.
- To explore potential applications in spintronics and magnetoelectrics.
Main Methods:
- Synthesis of a mixed-valence chromium(II/III) triazolate compound.
- Employing the phenomenon of itinerant ferromagnetism.
- Characterization of magnetic ordering temperature (TC) and magnetoresistance.
Main Results:
- Achieved ferromagnetic ordering at TC = 225 K, the highest reported for a metal-organic framework.
- Demonstrated itinerant ferromagnetism via a double-exchange mechanism.
- Observed a large negative magnetoresistance of 23% at 5 K, indicating barrierless charge transport below TC.
Conclusions:
- The developed chromium triazolate MOF exhibits unprecedented high-temperature ferromagnetism.
- The double-exchange mechanism facilitates efficient charge transport and significant magnetoresistance.
- These findings suggest promising applications for coordination solids in magnetoelectrics and spintronics.
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