Molecular Cluster Magnets

The following sections are included:

• PREFACE

• CONTENTS

The following sections are included:

• Convergent Self-assembly
  • Introduction and overview
  • Polytopic ligands for [n × n] square grids–design and self-assembly
  • Thermodynamic aspects of the formation of convergent self-assembled grid architectures

• Ligands and Complexes
  • Ditopic ligands and their complexes
    • Homometallic complexes
      • [2 × 2] grids with heterocyclic diazine (N₂) bridging ligands
      • Ditopic ligands with more remote coordination pockets
      • Other polynuclear oligomers with remote ditopic ligands
      • [2 × 2] grids with single atom μ-O and μ-S bridging ditopic ligands
      • Ditopic hydrazone ligands with both μ-O or μ-NN bridging modes
      • Higher order oligomeric clusters based on ditopic ligands
  • Heterometallic [2 × 2] and mixed spin state grids

• Symmetric tritopic ligands and their complexes
  • Homometallic [3 × 3] grids
  • Heterometallic and mixed spin state [3 × 3] grids

• Tetratopic ligands and complexes
  • Homometallic [4 × 4] grids

• Pentatopic ligands and their complexes
  • Homometallic [5 × 5] grids

• Other Oligomers in the Assembly Process
  • Incomplete grids, clusters and chains

• Nano-scale Molecular-Based Devices?

• Conclusions and Future Perspectives

• Acknowledgments

• References

The following sections are included:

• Introduction

• A Brief Introduction to the Physics of SMMs

• Further SMMs Based on Mn(III)
  • The largest SMM; a [Mn₈₄] torus
  • Record spin number, S_T = 83/2, but no slow relaxation
  • Record magnetic anisotropy barrier; a Mn₆ cluster
  • Quantum entanglement between SMMs; first discovered in a pair of Mn₄ clusters
  • clusters with an S = 9/2 ground state
  • The family of “rhombic” SMMs
  • Oxime bridged SMMs with the core and S_T = 6
  • Magnetostructural correlations within a family of SMMs

• MMs Based on Fe(III) Ion

• New SMMs Based on Divalent 3d-Ions

• Slow Relaxation in Complexes Involving 4f-Elements
  • Single atom magnets
  • Polymetallic 4f-complexes
  • Heterometallic 3d-4f SMMs

• Metallocyanate Based SMMs

• Conclusions

• References

The following sections are included:

• The Unique Magnetic Polyoxometalate V₁₅

• Structure and Superexchange Pathways

• Exchange Interactions within the Triangle Model
  • Isotropic exchange within the triangle model
  • ‘Accidental’ degeneracy and spin-frustration
  • Pseudo-angular momentum representation
  • Antisymmetric exchange, zero-field splitting
  • Ab initio calculations

• Zeeman Levels, Magnetic Anisotropy

• Electron Paramagnetic Resonance
  • EPR spectrum of V₁₅: Role of antisymmetric exchange and selection rules
  • Discussion of the experimental EPR data

• Static Magnetization
  • The theoretical model
  • Discussion of the experimental magnetization data

• Dynamic Properties, Relaxation, Spin Dynamics
  • Relaxation mechanisms and magnetic hysteresis
  • Spin dynamics in the muon scattering experiment
  • Rabi oscillations and implementation of molecular magnets in quantum computing

• Spin-vibronic Interaction
  • Hamiltonian of spin-vibronic coupling
  • Adiabatic surfaces
  • Influence of the Jahn-Teller effect on the magnetization
  • Estimation of the vibronic parameters for V₁₅

• Role of Structural Deformations
  • Zero-field splitting in a scalene triangular system
  • Discussion of inelastic neutron scattering experiments
  • Energy pattern of a scalene triangular system
  • Magnetic properties of the scalene systems
  • Field induced Jahn-Teller instability

• NMR Experiments

• Conclusions and Outlook

• Acknowledgements

• References

The following sections are included:

• Introduction

• Neutron Scattering: Basic Principles
  • Neutron scattering cross section
    • Nuclear scattering
    • Magnetic scattering
  • The time-of-flight technique

• Exchange Interaction: A Spectroscopic Measurement
  • Spin dynamics in antiferromagnetic molecular rings
    • Elementary excitations in antiferromagnetic rings

• Probing Quantum Coherence
  • Tunneling of the Néel vector
  • Quantum oscillations of the total spin

• Zero-Field Splitting Anisotropy in High Spin Clusters
  • The giant spin approximation and beyond
    • Beyond the giant spin approximation

• References

The following sections are included:

• Beyond the Giant Spin Approximation (GSA)

• Discrete Clusters-of-Clusters

• Pulsed EPR

• References

The following sections are included:

• Introduction
  • Scope and purpose
  • Introduction to the Heisenberg Hamiltonian
  • Usefulness and limitations of matrices

• Quantum Monte Carlo Simulations
  • Avoiding the ‘roadblock’ of large matrices
  • Energy spectrum for symmetric rings
  • Applications to heterometallic rings
  • Applications to frustrated magnetic molecules

• Classical Spin Dynamics Simulations
  • The classical Heisenberg Hamiltonian
  • Classical Monte Carlo simulations
    • The spin equations of motion
  • Heat bath simulational methods
  • Revealing novel physics in magnetic molecules with classical methods
    • Competing spin phases and exchange disorder in the Keplerate type molecules {Mo₇₂Fe₃₀} and {Mo₇₂Cr₃₀}
    • Metamagnetic phase transitions in magnetic polytopes
    • Critical slowing-down in Heisenberg magnetic molecules

• Summary

• References

The following sections are included:

• Index