Carbon Based Magnetism

Carbon Based Magnetism is the most complete, detailed, and accurate guide on the magnetism of carbon, the main element of living creatures. Written by the leading experts in the field, the book provides a comprehensive review of relevant experimental data and theoretical concepts related to the magnetism of metal-free carbon systems. These systems include carbon based compounds, namely organic radical magnetic systems, and magnetic materials based on carbon structures. The aim is to advance the understanding of the fundamental properties of carbon.

This volume discusses all major modern hypotheses on the physical nature of magnetic ordering in carbon systems. The first chapters deal with magnetic ordering mechanisms in p-electron systems as well as molecular magnets with spins residing only in p-orbitals. The following chapters explore the magnetic properties of pure carbon, with particular emphasis on nanosized carbon systems with closed boundary (fullerenes and nanotubes) and with open boundary (structures with edge-localized magnetic states). The remaining chapters focus on newer topics: experimental observation and theoretical models for magnetic ordering above room temperature in pure carbon. The book also includes twenty three review articles that summarize the most significant recent and ongoing exciting scientific developments and provide the explanation. It also highlights some problems that have yet to be solved and points out new avenues for research.

This book will appeal to physicists, chemists and biologists.

• The most complete, detailed, and accurate Guide in the magnetism of carbon
• Dynamically written by the leading experts
• Deals with recent scientific highlights
• Gathers together chemists and physicists, theoreticians and experimentalists
• Unified treatment rather than a series of individually authored papers
• Description of genuine organic molecular ferromagnets
• Unique description of new carbon materials with Curie temperatures well above ambient.

Physicists, Chemists and Biologists.

Editors’ Preface

Foreword

Chapter 1: Localized Spins Exchange-coupled with Itinerant Electrons in Organic π-electronic System

1 Preface

2 High Spin Hydrocarbons as a Model for One-dimensional Organic Ferromagnet

3 Spin Alignment Based on Itinerant Electron

4 Spin Alignment via Charge Transfer Interaction

5 Design of Spin-polarized Donors

6 Molecular and Crystal Design for Organic Ferromagnetic Metal

7 Conducting and Magnetic Properties of Networked Gold Nanoparticles Connected by Spin-polarized Molecular Wires

8 Summary

Chapter 2: Magneto-structural Correlations in π-Conjugated Nitroxide-based Radicals: Hydrogen-bonds and Related Interactions in Molecular Organic Solids

1 Introduction

2 Exchange and Crystal Assembly in Phenolic Nitronynitroxides

3 Bio-inspired Molecular Recognition for Crystal Assembly

4 Exchange and Crystal Assembly in Nitronylnitroxides with Hydrogen-bonding Azaarenes

5 Exchange and Crystal Assembly in Tert-butylnitroxides with Hydrogen-bonding Azaarenes

6 Exchange and Crystal Assembly in Cyclic Aza-Radicals Bearing Carboxylic Acid Groups

7 Exchange and Crystal Assembly in Aryl Tert-butylnitroxides Bearing Carboxylic Acid Groups

8 Conclusion

Acknowledgements

Chapter 3: Persistent High-spin Organic Polyradicals

1 Introduction

2 Spin Alignment of Non-Kekulé and Non-Disjoint Molecules

3 π-conjugated Polymers Bearing Aminium Cationic Radicals for High-spin Alignment at Room Temperature

4 m-phenylene-connected and Cross-conjugated Arylaminium Cationic Radicals

5 Two-Dimensionally Extended Poly(aminium cationic radical)s

Chapter 4: Verdazyl-based Magnetic Systems

1 Introduction

2 General Magnetic Properties of Verdazyl Radical Crystals

3 Ferromagnetism in Verdazyl Radical Crystals

4 Antiferromagnetism in Verdazyl Radical Crystal

5 Weak Ferromagnetism in Verdazyl Radical Crystals

6 Spin Peierls Transition in Verdazyl Radical Crystals

7 Spin Frustration in Verdazyl Radical Crystals

8 Magnetic Property of Verdazyl Radical Alloy

9 Photo-Excited High Spin States on π-Conjugated Verdazyl Radicals

10 Transition Metal Complex of Verdazyl Radicals

11 Magnetic Conductors Based on Verdazyl Radicals

Chapter 5: Quantum Spin Magnetism in Nitroxide-based Compounds

1 Introduction

2 A Zigzag Spin Chain, F2PIMNH [14]

3 Polyradical Approach

4 Spin Ladder

5 Ferrimagnetism

6 Spin Frustration

7 Pressure Effects

8 Field Induced Magnetic Ordering

Acknowledgements

Chapter 6: The Magnetism of π-Orbitals under Pressure

1 Introduction

2 Experiments under Pressure

3 Pressure Effects on Genuine Organic Antiferromagnets

4 Pressure Effects on Genuine Organic Ferromagnets

5 Pressure Effects on Sulfur-based Organic Magnets with Ferromagnetic Moments

6 Other Interesting Pressure Effects on Thermally and Structurally Unstable Compounds

7 Conclusion

Chapter 7: Spin Density Distribution and Interaction Mechanisms in Thiazyl-based Magnets

1 Introduction

2 Spin Densities in the Dithiadiazolyl Ring

3 Spin Density Studies on thep-nitro-tetrafluorophenyl- dithiadiazolyl radical (3)

4 Magnetic Interactions in Dithiadiazolyl Radicals

5 Other Thiazyl Radicals

6 Conclusions

Chapter 8: Magnetic Bistability in Molecule-based Magnetic Materials

1 Introduction

2 Magnetic Bistability in Organic Radical Solids

3 Molecule-based Magnetic Bistable Materials

4 Summary

Chapter 9: The Nature of Effective Exchange Interactions

1 Introduction

2 The Nature of Chemical Bonds and Magnetic Interactions

3 Less Screening Rule and Hund Rule

4 Spin Polarization Rule and Related Spin Alignment Rules

5 Intermolecular Spin Alignment Rules

6 Conclusion

Chapter 10: Magnetism of Fullerene Charge-transfer Complexes

1 Introduction

2 TDAE-C60

3 Higher Fullerenes Reduced with TDAE

4 Reduction of C60 with Different Organic or Organometallic Donors

5 Charge Transfer Complexes of C60 Derivatives

6 Intercalation of Magnetic Ions

Chapter 11: Diamagnetism of Diamond and Graphite

1 Introduction

2 Theory of (Dia)magnetism

3 Diamagnetism of Diamond

4 Graphite: Electronic Band Structure

5 Graphite: Magnetic Susceptibility

7 Concluding Remarks

Acknowledgements

Chapter 12: Electronic and Magnetic Properties of Nanographites

1 Introduction

2 Electronic States of Nanographite Ribbons

3 Electronic States in a Magnetic Field

4 Bearded Edge and Cove Edge

5 Connection with Anisotropic Superconductivity

6 Orbital Diamagnetism and Pauli Paramagnetism

7 Magnetic Instability

8 Summary

Chapter 13: Flat-band Ferromagnetism in Organic Crystals

1 Introduction

2 Effective Models for Nano-graphite

3 Nano-graphite and Edge States

4 Flat-band Ferromagnetism in Organic Materials

5 Materials Design of Magnetic Carbon

6 Summary and Discussion

Chapter 14: Magnetism in Nanometer-scale Materials that Contain No Magnetic Elements

1 Preamble

2 Density Functional Theory

3 Edge States of Zigzag-shaped Graphite Ribbons

4 Magnetic Ordering Related to Border States

5 Magnetic Carbon Nanotubes

6 Magnetism on Si Surfaces

7 Concluding Remarks: Quantum Design of Nanomagnets

Acknowledgements

Chapter 15: Interactions and Disorder in 2D Graphite Sheets

1 Introduction

2 The Elecronic Structure of Graphene Sheets

3 The Long Range Coulomb Interactions in Graphite

4 Effects of Disorder

5 Combined Effects of Disorder and the Electronic Interactions

6 Coupling between Graphene Layers

7 Conclusions

Chapter 16: The Magnetic Nature of Intrinsic and Irradiation-induced Defects in Carbon Systems

1 Introduction

2 Methodology

3 Magnetic Properties of the Frenkel Pair in Carbon Systems

4 Magnetism Stimulated by Non-magnetic Impurities

5 Conclusions and Outlook

Chapter 17: Unconventional Magnetic Properties of Nanographite

1 Introduction

2 What Theory Predicts on the Electronic and Magnetic Structure of Nanographene

3 Electronic and Magnetic Features of Nanographite and Networked Nanographites

4 Nanographite Grown in sp2/sp3 Mixed Nano-carbon

5 Host-guest Interaction and Edge-state Spins

6 Summary

Acknowledgements

Chapter 18: Ferromagnetic and Superconducting Instabilities in Graphite

1 Introduction

2 Ferromagnetism in Carbon Materials: a Comparative Study

3 Oxygen adsorption Effect on the Magnetic Properties of Graphite

4 Coexistence of Superconducting and Ferromagnetic Instabilities in Graphite-sulfur Composites

5 Discussion and Concluding Remarks

Chapter 19: Induced Magnetic Order by Ion Irradiation of Carbon-based Structures

1 Motivation

2 Irradiation Characteristics

3 Irradiation Effects

4 Annealing and Aging Effects

5 Conclusion and Open Issues

Acknowledgements

Chapter 20: Magnetic Properties of Novel Carbon Allotropes

1 Introduction

2 Strongly Paramagnetic and Ferromagnetic Pure Carbons

3 Causes of Para- and Ferromagnetism in Pure Carbon

4 Synthesis Techniques

5 Concluding Remarks

Chapter 21: McConnel Model for the Magnetism of C60-based Polymers

1 Introduction

2 C60-Polymers: A brief overview

3 Carbon Magnetism: A Member of a New Magnetic Class?

4 Defects in Carbon-based Materials

5 Theoretical Models

6 Magnetic C60 Polymers Revisited

7 Discussion and Conclusions

Acknowledgments

Chapter 22: The Mechanism of the Magnetic Interaction in Polymeric-C60 Fullerenes

1 Introduction

2 Methodological Considerations

3 The Cage-vacancy Mechanism

4 The Open-cage Mechanism

5 The Interfragment Bond-breaking Mechanism

6 Summary and Conclusions

Acknowledgments

Chapter 23: Ferromagnetism in Defective Polymerised C60

1 Introduction

2 Methodology

3 Pristine Rh-C60

4 Prototype Defective Structures: Vacancy Defects

5 Spontaneous Formation of Defects from Pressure

6 Spontaneous Formation of Defects from Pressure and Temperature

7 A Ferromagnetic Ground State in the presence of Hydrogen

8 Conclusions

Acknowledgements

Chapter 24: Ferromagnetic Carbonaceous Compounds

1 Introduction

2 Experimental Evidence

3 Summary of Experimental Observations

4 Theoretical Models

5 Conclusions

Subject Index