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Published on: July 4, 2016
Complex relaxation of trapped spin-states in spin crossover materials
Nadeem Natt1, Benjamin J Powell1
1School of Mathematics and Physics, The University of Queensland Brisbane Queensland 4072 Australia powell@physics.uq.edu.au.
Spin crossover (SCO) materials exhibit diverse relaxation dynamics. A new model explains these complex behaviors by linking crystal field theory with frustrated intermolecular interactions, revealing a rugged free energy landscape.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Chemical Physics
Background:
- Spin crossover (SCO) materials display a variety of relaxation dynamics, including exponential, sigmoidal, and multi-step kinetics.
- Understanding these dynamics is crucial for the development of advanced materials and devices.
Purpose of the Study:
- To reproduce and explain the full range of relaxation dynamics observed in SCO materials.
- To elucidate the role of intermolecular interactions and free energy landscapes in SCO material behavior.
Main Methods:
- Development of a semi-empirical, semi-classical model.
- Integration of crystal field theory with elastic intermolecular interactions.
- Analysis of frustrated intermolecular interactions and their impact on ordered phases.
Main Results:
- The model successfully reproduces diverse relaxation dynamics (exponential, sigmoidal, stretched exponential, multi-step, mixed kinetics).
- Frustrated intermolecular interactions lead to multiple energetically competitive ordered phases, even with a single SCO site.
- A rugged free energy landscape is identified as the cause of dynamic disorder and complex SCO dynamics.
Conclusions:
- The proposed model provides a unified explanation for the complex relaxation dynamics in SCO materials.
- Frustrated intermolecular interactions and the resulting rugged free energy landscape are key factors driving dynamic disorder.
- These mechanisms are relevant for understanding dynamics in a broader range of complex systems, including proteins and quantum materials.
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