Physics of Transition Metal Oxides

Front Cover
The fact that magnetite (Fe304) was already known in the Greek era as a peculiar mineral is indicative of the long history of transition metal oxides as useful materials. The discovery of high-temperature superconductivity in 1986 has renewed interest in transition metal oxides. High-temperature su perconductors are all cuprates. Why is it? To answer to this question, we must understand the electronic states in the cuprates. Transition metal oxides are also familiar as magnets. They might be found stuck on the door of your kitchen refrigerator. Magnetic materials are valuable not only as magnets but as electronics materials. Manganites have received special attention recently because of their extremely large magnetoresistance, an effect so large that it is called colossal magnetoresistance (CMR). What is the difference between high-temperature superconducting cuprates and CMR manganites? Elements with incomplete d shells in the periodic table are called tran sition elements. Among them, the following eight elements with the atomic numbers from 22 to 29, i. e. , Ti, V, Cr, Mn, Fe, Co, Ni and Cu are the most im portant. These elements make compounds with oxygen and present a variety of properties. High-temperature superconductivity and CMR are examples. Most of the textbooks on magnetism discuss the magnetic properties of transition metal oxides. However, when one studies magnetism using tradi tional textbooks, one finds that the transport properties are not introduced in the initial stages.
 

Contents

Introduction
1
12 Crystal Structure and Physical Properties
4
13 Exchange Interaction
8
14 Orbital Degeneracy
15
15 DoubleExchange Interaction
19
16 Magnetic Anisotropy
22
162 Anisotropic Exchange Interactions
25
References
34
412 Electronic Hamiltonian and Exchange Interaction
170
413 JahnTeller Effect and Cooperative JahnTeller Effect
178
414 Phase Diagram and Orbital Order
182
415 Orbital Liquid State
186
42 Manganite with Layered Structure
190
422 Stability of Orbital and Magnetic Structure
193
423 Experiments for Spin and Orbital Correlation
194
43 Resonant Xray Scattering RXS
197

Cuprates
37
21 Underlying Electronic Structure of Cuprates
38
212 Model Hamiltonian
41
213 Superexchange Interaction CornerSharing Cuprates
43
214 Cyclic FourSpin Interaction
49
215 ZhangRice Singlet State
50
216 Optical Excitations
55
22 OneDimensional Cuprates
58
222 Realization of SpinCharge Separation
63
223 Charge Dynamics in Insulating Cuprates
68
224 Nonlinear Optical Response
74
225 Spin Dynamics in Insulating Cuprates
79
23 TwoDimensional Cuprates
80
231 Single Carrier in Mott Insulator
81
232 Phase Diagram
86
233 Optical Conductivity
90
234 SingleParticle Spectral Function
93
235 Chemical Potential
94
24 Summary
95
References
96
Theory of Superconductivity
101
31 The BCS Pairing Theory
103
32 Phonons in Solids
107
33 Phonons as Intermediate Bosons
108
34 Theory of the Antiferromagnetic Parent Compounds
111
35 The JordanWigner Transformation and Flux Tubes
116
36 Coherent States Grassman Variables and Flux Tubes
120
37 MeanField Approximations and Flux States
122
38 Bogoliubov Theory for a Bose Superfluid
124
39 Auxiliary Particle Methods
126
310 Magnetic Exchange Interactions via Intermediate Bosons
130
311 The MeanField RVB Slave Boson Theory
131
312 The Gutzwiller Projection and a Ul Symmetry
136
313 Auxiliary Particles and the Introduction of Flux Tubes
137
314 Spin Pairing
140
315 Fermionic Excitations in an Antiferromagnet
141
316 SU3 Approach to Hole Coherent States
143
317 The Effective Exchange for Coherent Doping
147
318 SO5 Theory
150
319 SO5 and SU3 Theories
155
320 Gossamer Superconductivity
158
321 Summary
163
References
165
Manganites
167
431 Experiments
198
432 Scattering Cross Section
200
433 Azimuthal Angle Dependence
203
434 Mechanism of RXS
206
435 Microscopic Calculations of the RXS Intensity
209
44 Orbital Excitation
211
45 Other OrbitalRelated Topics
216
46 Summary
219
51 Introduction
225
52 Orbital States
226
522 Perovskite Vanadates
229
53 Metal Insulator Transition
230
54 Electronic State and Model Hamiltonian
231
55 Summary
238
Cobaltates
241
62 Thermoelectric Materials and Cobalt Oxides
245
63 Thermoelectric Effect
246
64 Linear Response Theory for Thermoelectric Systems
250
Approach from High Temperature Side
252
66 Spin and Orbital States and the Thermopower
254
67 Thermopower of the Degenerate Electron Gas
257
References
259
Quantum Effects in Orbitally Degenerate Systems
261
71 Systems with eg Orbital Degeneracy
262
712 OrbitalOnly Model
269
713 OrbitalCharge Coupling Orbital Polarons
272
714 Orbital Liquids Anomalous Transport
279
72 Systems with t2g Orbital Degeneracy
282
721 SpinOrbital Model
283
722 OrbitalOnly Model
291
73 High Spin Systems with t2g Orbital Degeneracy
298
732 SpinOrbital Dimerization
302
74 Summary
306
A Optical Conductivity
311
The Lanczos Method
317
C Projection Method Memory Function Method Composite Operator Method
321
DI Seebeck Effect
323
D2 Peltier Effect
325
D3 Thomson Effect
326
Thomsons Considerations
328
D5 The Third Law of Thermodynamics and Thermoelectric Response in Solids
330
References for Appendices
333
Index
335
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