Targets: Green Energy, Computation & Data Storage
Targets: Biosensing, hyperthermia, MRI Contrast, Magnetic Cooling
Targets: Computation & Data Storage, Spintronics
The utility of all magnetic materials comes down to two major components: crystal structure and domain structure. While the crystal structure is largely dictated by the chemical composition, the domain structure (size, shape, surface morphology) offers a wide parameter space for altering the magnetic parameters of a magnetic material. Using colloidal nanochemistry, we can precisely tune the many aspects of domain structure to rationally optimize the properties of isolated, nanoscale domains. These optimized domains can then be converted to dense solids through low temperature and pressure cross-linking procedures to build up new custom-tuned magnetic materials.
A wide variety of current and proposed technologies depend on the superparamagnetic properties of nanomaterials constructed from simple mono and bimetallic oxides. Key factors affect their utility are saturation magnetization, blocking temperature, and the relaxation time. Magnetization and the rough blocking temperature often show a simple correlation with the size of the particle; however, the timescale can follow complex dynamics depending on the size, shape, interparticle distance, and temperature. Since many applications require a specific measurement timescale, even a small mismatch between the required application temperature and the relaxation behavior can drastically reduce performance. The particle size is often used as a handle for tuning their magnetic properties; however this is only one of the factors that can tune magnetism in these incredibly useful materials. Size, shape, phase, and heterostructure can all be used to maximize signal while enhancing the utility for specific applications.
Though often characterized in isolation, molecular magnets must be interfaced with other materials for implementation in any technology. Extending concepts such as exchange-spring, exchange bias, and magnetic proximity effects to hybrid molecular/nanscale materials offers limitless opportunity for the discovery of new properties. The methods of colloidal nanochemistry give us the means to rapidly interface and characterize new materials.