[内容简介]
The main focus of the book is to present the effects of nanostructuring on superconducting critical parameters. Optimizing systematically flux and condensate confinement in various nanostructured superconductors, ranging from single nano-cells to their huge arrays, critical fields and currents can be increased up to their theoretical limits, thus drastically improving the potential for practical applications of nanostructured superconductors.
[目次]
1 Introduction 1
1.1 Quantization and confinement in nano-materials 3
1.2 Nanostructuring 4
1.3 Confining the superconducting condensate 6
1.4 Nucleation of superconductivity in presence of spatially modulated magnetic fields 11
1.5 Vortex matter in superconductors 13
1.5.1 The structure of a single vortex 18
1.5.2 The vortex lattice - general considerations 21
1.5.3 Vortex lattices in thin films 24
1.5.4 Vortex lattices in type-1.5 superconductors 24
1.6 Flux pinning 32
1.6.1 Structural pinning 33
1.6.2 Magnetic pinning 33
2 Individual Nanostructures 37
2.1 Line 38
2.2 Loop 39
2.3 Disc 44
2.4 The cross-over from loop to dot 50
2.5 Symmetry-induced antivortices in mesoscopic superconductors 57
2.5.1 Square 58
2.5.2 Triangle 63
2.5.3 Rectangles 69
2.6 The magnetization of singly connected nanostructures 73
2.6.1 Disc 75
2.6.2 Triangle 80
2.6.3 Square 82
2.7 Dynamic effects in mesoscopic structures 86
2.7.1 Rectification effects in a triangle 86
2.7.2 Reversal of the diode effect 88
2.7.3 The diode effect in a disk 92
2.7.4 Comparison with a theoretical model 93
2.8 Hybrid individual cells 97
2.8.1 Square with magnetic dot 98
2.8.2 Phase shifter 104
3 Clusters of Nanocells 111
3.1 One-dimensional clusters of loops 111
3.2 Two-dimensional clusters of antidots 117
3.3 Magnetically coupled loops 121
4 Laterally Nanostructured Superconductors 127
4.1 The T_c(H) phase boundary of superconducting films with an antidot lattice 127
4.2 Pinning in laterally nanostructured superconductors 136
4.2.1 Pinning by an antidot or a columnar defect 137
4.2.2 Regular pinning arrays 139
4.2.3 Regular pinning arrays with n_s = 1 139
4.2.4 Multiquanta vortex lattices (n_s > 1) 156
4.2.5 Crossover from pinning arrays to networks (n_s >> 1) 170
4.2.6 Composite antidot lattices 174
4.3 Ratchet effects in antidot lattices 183
4.3.1 Vortex rectification in films with asymmetric pinning 183
4.3.2 Controlled multiple reversals of a ratchet effect 190
4.3.3 The origin of reversed vortex ratchet motion 196
5 Superconductor-Ferromagnet Hybrid Systems 203
5.1 Field polarity dependent vortex pinning in laterally nano-structured S/F systems 204
5.1.1 Vortex pinning by magnetic dots 206
5.1.2 Commensurate vortex domain formation 215
5.2 Field induced superconductivity 220
5.3 Dipole-induced vortex ratchet effects 225
5.3.1 Generation of vortex-antivortex pairs 226
5.3.2 Switching rectification properties 231
5.4 Superconductivity in stray fields of magnetic domains 235
5.4.1 Domain superconductivity and domain-wall superconductivity 236
5.4.2 Direct visualization of reverse-domain superconductivity 242
5.4.3 Superconducting - normal-state junctions induced by stray magnetic fields 247
Concluding Remarks 257
Bibliography 261
Index 295