New Itinerant Electron Models of Magnetic Materials

ISBN-13: 9789811612732 / Angielski / Miękka / 2022

Gui-De Tang

Opis

This book highlights a series of new itinerant electron models proposed based on the experimental results of electron spectra obtained since 1970. Although conventional magnetic ordering models were established before 1960, many problems remain to be solved. The new models in this book include an O 2p itinerant electron model for magnetic oxides, a new itinerant electron model for magnetic metals, and a Weiss electron pair model for the origin of magnetic ordering energy of magnetic metals and oxides. With these models, the book explains typical magnetic ordering phenomena including those that cannot be explained using conventional models. These new models are easier to understand than the conventional magnetic ordering models.

Spis treści

1 Introduction

References

2. Electron shell structure of free atoms and valence electrons in crystals

2.1 Electron shell structure of free atoms

2.2 A simple introduction to classical crystal binding theory for typical magnetic materials

2.3 Effective radii of ions in crystals

2.4 Electron binding energy originating from ions in crystals

References

3. A simple introduction to basic knowledge of magnetic materials 

3.1 Classification of matters based on magnetic properties

3.2 Magnetic domain and domain wall

3.3 Basic parameters of magnetic materials

3.4 Magnetic ordering models in conventional ferromagnetism

References

4. Difficulties related to conventional magnetic ordering models

4.1 Disputes over the distributions of Mn and Cr cations in spinel ferrites

4.2 Difficulties in describing the observed magnetic moments of perovskite manganites

4.3 Relationship between magnetic moment and electrical resistivity in typical magnetic metals

4.4 Puzzle for the origin of magnetic ordering energy

References

5. O 2p itinerant electron model for magnetic oxides

5.1 A simple introduction to early investigations of ionicity

5.2 Study of ionicity of spinel ferrites

5.3 Experimental studies of O 2p holes in oxides

5.4 Study of negative monovalent oxygen ions using X-ray photoelectron spectra 

5.5 O 2p itinerant electron model for magnetic oxides (IEO model)

5.6 Relationship between the IEO model and the conventional models 

References

6. Magnetic ordering of typical spinel ferrites

6.1 Method fitting magnetic moments of typical spinel ferrites

6.2 Caion distribution characteristics in typical spinel ferrites

References

7. Experimental evidences of the IEO model obtained from spinel ferrite

7.1 Additional antiferromagnetic phase in Ti doped spinel ferrites

7.2 Amplification of spinel ferrite magnetic moment due to Cu substituting for Cr

7.3 Unusual infrared spectra of Cr ferrite

References

8. Spinel ferrites with cant angle magnetic coupling

8.1 Spinel ferrites with Fe ratio being less than 2.0 per molecule

8.2 Spinel ferrites containing nonmagnetic cations

References

9. Magnetic ordering and electrical transport of perovskite manganites

9.1 Ferromagnetic and antiferromagnetic coupling in typical perovskite manganites

9.2 Spin-dependent and spin-independent electrical transport of perovskite manganites

9.3 Experimental evidences on canting magnetic structure in perovskite manganites

9.4 Magnetic coupling between the two sublattices in perovskite praseodymium manganites

9.5 Substituting for Mn in perovskite praseodymium manganites

9.6 Experimental evidences for antiferromagnetic coupling between divalent and trivalent Mn ions in perovskite manganites

References

10. Anti-ferromagnetic ordering in oxides with sodium chloride structure

10.1 Characteristics of antiferromagnetic oxides with sodium chloride structure

10.2 Difference between magnetic structures of manganese monoxide and lanthanum manganite

References

11. Itinerant electron model for magnetic metals 

11.1 Experimental and theoretical studies for atomic magnetic moments in metals

11.2 Itinerant electron model for magnetic metals (IEM model)

References

12. Study on the origin of magnetic ordering energy for magnetic materials

12.1 Weiss molecular field

12.2 Thermal expansivity of perovskite manganites near the Curie temperature

12.3 Weiss electron-pair (WEP) model for magnetic ordering energy

12.4 Explanation for the Curie temperature difference of typical magnetic materials 

12.5 Explanation for Cu ratio dependence of resistivity and Curie temperature for NiCu alloys

References

13. Prospects and challenges for future work

13.1 Other factors affecting magnetic ordering energy

13.2 Magnetic ordering energy used in DFT calculation

13.3 Application of IEO and IEM model

References

Appendixes

A. Electron structure and ionization energies of free atoms

B. Effective ion radii reported by Shannon

C. Symbol notes

O autorze

Dr. Gui-De Tang is Professor at the Department of Physics, Hebei Normal University, and Visiting Scholar, the Institute of Physics, Chinese Academy of Sciences. He was Visiting Scholar in Laboratoire de Magnétisme et Matériaux Magnétiques, Meudon, France, in 1991.