Modern Physics of Ferroelectrics: Essential Background
Karin M. Rabe, Matthew Dawber, Celine Lichtensteiger,
Charles H. Ahn, and Jean-Marc Triscone ....................... 1
1 Introduction ................................................. 1
2 Switching and Hysteresis Loops ............................... 2
3 Crystallographic Signature of Ferroelectricity ............... 6
4 Materials .................................................... 8
4.1 Perovskite Oxides ....................................... 8
4.2 LiNb03 .................................................. 4
4.3 Layered Oxide Ferroelectrics ........................... 15
4.4 Other Ferroelectric Oxide Families ..................... 17
4.5 Magnetic Ferroelectric Oxides .......................... 18
4.6 Electronic Ferroelectrics .............................. 19
4.7 Nonbulk Ferroelectrics ................................. 19
5 Applications of Ferroelectric Materials ..................... 20
5.1 Pyroelectric and Piezoelectric Devices ................. 20
5.2 Ferroelectric Memory Technology ........................ 21
5.3 Potential Future Applications .......................... 21
5.3.1 Ferroelectric Nanostructures .................... 21
5.3.2 Field-Effect Devices ............................ 22
5.3.3 Ferroelectric Device Fabrication Using Atomic
Force Microscopy ................................ 22
5.3.4 Ferroelectric Cooling Devices ................... 23
6 Note from the Editors ....................................... 23
References .................................................. 23
Index ....................................................... 29
Theory of Polarization: A Modern Approach
Raffaele Resta and David Vanderbilt ......................... 31
1 Why is a Modern Approach Needed? ............................ 31
1.1 Fallacy of the Clausius-Mossotti Picture ............... 32
1.2 Fallacy of Defining Polarization via the Charge
Distribution ........................................... 34
2 Polarization as an Adiabatic Flow of Current ................ 36
2.1 How is Induced Polarization Measured? .................. 36
2.2 How is Ferroelectric Polarization Measured? ............ 38
2.3 Basic Prescriptions for a Theory of Polarization ....... 40
3 Formal Description of the Berry-Phase Theory ................ 41
3.1 Formulation in Continuous k-Space ...................... 42
3.2 Formulation in Discrete k-Space ........................ 44
3.3 The Quantum of Polarization ............................ 46
3.4 Formal Polarization as a Multivalued Vector Quantity ... 48
3.5 Mapping onto Wannier Centers ........................... 50
4 Implications for Ferroelectrics ............................. 52
4.1 Spontaneous Polarization ............................... 53
4.2 Anomalous Dynamical Charges ............................ 54
4.3 Piezoelectric Properties ............................... 55
5 Further Theoretical Developments ............................ 57
5.1 Polarization in an Applied Electric Field .............. 57
5.2 Interface Theorem and the Definition of Bound Charge ... 58
5.3 Many-Body and Noncrystalline Generalizations ........... 61
5.4 Polarization in Kohn-Sham Density-Functional Theory .... 62
5.5 Localization, Polarization, and Fluctuations ........... 63
6 Summary ..................................................... 64
References .................................................. 65
Index ....................................................... 67
A Landau Primer for Ferroelectrics
Premi Chandra, Peter B. Littlewood .......................... 69
1 Introduction ................................................ 69
2 Landau-Devonshire Theory .................................... 74
2.1 General Phenomenology .................................. 74
2.2 Second-Order (Continuous) Transition ................... 75
2.3 First-Order (Discontinuous) Transition ................. 76
2.4 Coupling to Strain ..................................... 79
2.5 Domains ................................................ 81
3 Landau Ginzburg Theory ...................................... 84
3.1 General Considerations ................................. 84
3.2 The Polarization Correlation Function .................. 85
3.3 The Levanyuk Ginzburg criterion ........................ 86
3.4 Displacive and Order-Disorder Transitions .............. 88
3.5 Recent Developments in Bulk Ferroelectricity ........... 91
4 Reduced Size and Other Boundary Effects ..................... 92
4.1 General Discussion ..................................... 92
4.2 The Polarization at the Boundary ....................... 93
4.3 Depolarization Effects ................................. 96
4.4 Misfit Epitaxial Strain ............................... 100
4.5 Inhomogeneous Effects ................................. 102
5 Summary and (Some) Open Questions .......................... 104
References ................................................. 106
Index ...................................................... 115
First-Principles Studies of Ferroelectric Oxides
Karin M. Rabe and Philippe Ghosez .......................... 117
1 Introduction ............................................... 117
2 First-Principles Methods ................................... 118
3 Results for Perovskite Oxide Compounds ..................... 123
3.1 Ground-State Structure ................................ 124
3.2 Phonons, Lattice Instabilities and Polarization ....... 127
3.3 Polarization-Strain Coupling .......................... 136
3.4 Dielectric and Piezoelectric Responses ................ 137
3.5 Results at Nonzero Temperature ........................ 140
4 Results for Other Ferroelectric Oxide Compounds ............ 143
5 Results for Solid Solutions ................................ 146
6 Results for Defects ........................................ 150
7 Results for Surfaces, Thin Films, Superlattices,
Nanowires and Nanoparticles ................................ 152
8 Challenges and Prospects ................................... 154
References ................................................. 156
Index ...................................................... 172
Analogies and Differences between Ferroelectrics and
Ferromagnets
Nicola A. Spaldin .......................................... 175
1 Fundamentals ............................................... 177
1.1 Understanding the Origin of Spontaneous
Polarization .......................................... 177
1.1.1 What Causes Ferroelectricity? .................. 177
1.1.2 What Causes Ferroinagnetism? ................... 184
1.2 Domains ............................................... 188
2 Applications ............................................... 194
2.1 Ferroelectric Random Access Memories .................. 196
2.2 Magnetoresistive Random Access Memories ............... 196
3 Multiferroics .............................................. 198
3.1 The Scarcity of Ferromagnetic Ferroelectrics .......... 199
3.2 Magnetoelectric Coupling .............................. 200
3.3 Some Materials Examples ............................... 201
3.3.1 BiFeO3 ......................................... 201
3.3.2 BiMnO3 ......................................... 204
3.3.3 YMnO3 .......................................... 206
3.3.4 ТbМnO3 ......................................... 209
3.4 Composites ............................................ 209
4 Outlook .................................................... 210
References ................................................. 211
Index ......................................................... 216
Growth and Novel Applications of Epitaxial Oxide Thin Films
Agham-Bayan Posadas, Mikk Lippmaa, Fred J. Walker, Matthew
Dawber, Charles H. Ahn, and Jean-Marc Triscone ............. 219
1 Introduction ............................................... 219
2 Thin-Film Growth of Complex Oxides ......................... 221
2.1 Vacuum Chamber ........................................ 221
2.2 Temperature Control and Monitoring .................... 222
2.3 Pulsed Laser Deposition ............................... 227
2.3.1 Laser .......................................... 228
2.3.2 Targets ........................................ 230
2.3.3 Ablation Process ............................... 232
2.3.4 Film Growth Using PLD .......................... 235
2.4 Sputter Deposition .................................... 238
2.4.1 Sputtering Process ............................. 238
2.4.2 The Sputtering of Insulators ................... 239
2.4.3 Process Gas .................................... 240
2.4.4 Preferential Sputtering ........................ 242
2.4.5 Technical Considerations in Sputter
Deposition ..................................... 242
2.4.6 Reactive Sputtering ............................ 244
2.5 Oxide Molecular Beam Epitaxy .......................... 244
2.5.1 Hardware ....................................... 246
2.5.2 RHEED .......................................... 247
2.5.3 Fundamentals of Growth ......................... 249
2.5.4 Alkaline-Earth Oxide Growth .................... 253
2.5.5 Perovskite Growth .............................. 254
3 Substrates ................................................. 257
4 Applications of Epitaxial Oxide Thin Films ................. 269
4.1 Strain Engineering and Superlattices .................. 270
4.1.1 Strain Engineering in Epitaxial Thin Films ..... 270
4.1.2 Strain in Superlattices ........................ 271
4.1.3 Electrostatic Coupling Between Layers .......... 274
4.1.4 Selected Examples of Material Combinations ..... 274
4.1.5 X-Ray Characterization of Superlattices ........ 277
4.2 Crystalline Oxides on Semiconductors (COS) ............ 279
4.2.1 Layer-Sequenced COS Growth ..................... 281
4.2.2 How the Silicide Facilitates Epitaxy ........... 285
4.3 Conclusions ........................................... 289
References ................................................. 290
Index ...................................................... 304
Ferroelectric Size Effects
Celine Lichtensteiger, Matthew Dawber, and Jean-Marc
Triscone ................................................... 305
1 Size Effects in Ferroelectrics ............................. 305
2 Size Effects in the Ginzburg-Landau-Devonshire Theory ...... 306
3 Extrinsic Size Effects ..................................... 307
4 Effect of Screening ........................................ 308
4.1 Recent Experimental Work: Ultrathin Films on
Metallic Electrodes ................................... 310
4.1.1 Results of Combined Experimental and
Theoretical Investigations ..................... 316
4.1.2 Other Similar Studies .......................... 320
4.2 Scaling of the Coercive Field ......................... 321
4.3 Thin Films on Insulating Substrates ................... 322
5 Superlattices .............................................. 324
6 Other Geometries ........................................... 326
6.1 Nanoparticles ......................................... 327
6.2 Areal Size Effects .................................... 328
6.3 Self-Patterning ....................................... 328
6.4 Novel Ferroelectric Geometries ........................ 329
6.4.1 Nanotubes ...................................... 329
6.4.2 Nanowires - Nanorods ........................... 329
References ................................................. 330
Index ...................................................... 336
Nanoscale Studies of Domain Walls in Epitaxial
Ferroelectric Thin Films
Patrycja Paruch, Thierry Giamarchi, and Jean-Marc
Triscone ................................................... 339
1 Introduction ............................................... 339
2 Ferroelectric Domain Walls as Elastic Disordered Systems ... 340
3 Static and Dynamic Behavior of Elastic Disordered
Systems .................................................... 341
4 Experimental Observation of Domain-Wall Creep .............. 344
5 Domain-Wall Creep in a Commensurate Potential .............. 347
6 Domain-Wall Creep in a Random Potential .................... 351
7 Experimental Observation of Domain-Wall Roughness .......... 354
8 Domain Walls in the Presence of Random-Bond Disorder
and Dipolar Interactions ................................... 357
9 Recent Studies of Ferroelectric Domain-Wall Dynamics ....... 358
10 Conclusions ................................................ 359
References ................................................. 360
Index ...................................................... 362
APPENDIX A - Landau Free-Energy Coefficients
Long-Qing Chen ................................................ 363
1 BaTiO3 ..................................................... 364
2 SrTiO3 ..................................................... 365
3 PbZr1-x TixO3 (PZT) ......................................... 366
4 PbTiO3 ..................................................... 368
5 LiTaO3 and LiNbO3 .......................................... 368
6 Sr0.8Bi2.2Ta2O9 .............................................. 369
7 SrBi2Nb2O9 .................................................. 369
References ................................................. 370
Index ...................................................... 371
Appendix В — Material-Substrate Combinations Tables
Celine Lichtensteiger and Matthew Dawber ...................... 373
Index ......................................................... 385
|
