PHY 913 (Sect. 301):
Nanoscience and Nanotechnology
David Tomanek
Fall 2013
Topic 3: Magnetic Systems
- Stability of magnetic clusters
- Introduction
- Challenging problems:
- What makes nanostructures magnetic?
- What determines the relative abundance of
particular clusters?
- Are there magnetic magic numbers?
- Computational techniques
- Parametrized LCAO formalism
- Stoner model of magnetism and its application to clusters
- Monte Carlo Simulations for energy minimization
- Numerical Results
- Small Fe clusters: Comparison with other calculations
- Large Fe clusters: Predictions
- Origin of stability maxima
- Atomic packing
- Spin polarization
- Electronic shell closure
- Coated magnetic particles
- Bucky onions with a magnetic core
- Formation dynamics from defective carbon black
- Stability and Formation Dynamics of
Magnetic Cluster Assemblies
- Introduction
- Ferrofluids as complex dipolar fluids
- Challenging problems:
- Equilibrium structures?
- Effect of external field and temperature?
- Formation and disintegration dynamics?
- Experimental observation of complex structures
- "Magnetic marbles" as a model system
- Theoretical description
- Energetics of ferrofluids
- Dynamics of extended magnetic dipoles:
- Molecular dynamics with quaternion coordinates
- Dynamics in a strongly damped system
- Structure formation in ferrofluids
- Equilibrium structures
- T=0 structures in zero and nonzero field
- Interpretation based on continuum elasticity theory
- Thermally induced structural transitions
- Structural transitions induced by external fields
- Aggregation dynamics
- Zero field: Formation of closed structures and knots
- Nonzero field: Formation of branched structures
- Application of Magnetic Nanostructures
- Magnetic Memory
- Memory as a driven two-level system
- Population analysis in a canonical ensemble
- Structural transformations near a magnetic tip (
movie)
- Local medicaction release mechanism (
movie)
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