INTRODUCTION .................................................... 5
Chapter 1 SUPPRESSION OF ANTIFERROMAGNETIC ORDER .............. 12
1.1 Electronic structure near dopant .......................... 13
1.2 Magnon spectrum perturbation by a doped spin .............. 16
1.3 Effective interaction between localized spins ............. 20
1.4 Phase states at low temperatures .......................... 22
1.5 Static deformations and long-range magnetic order ......... 24
1.6 Concluding remarks ........................................ 30
Chapter 2 METALLIZATION IN DOPED SEMICONDUCTORS ............... 31
2.1 Model and basic results for 3D systems .................... 34
2.2 Spectrum and electronic properties of doped 2D metal ...... 43
2.3 Specifics of doped quasi-2D systems ....................... 50
2.4 Concluding remarks ........................................ 52
Chapter 3 IMPURITY STATES IN SUPERCONDUCTING SYSTEMS .......... 54
3.1 Green's functions for superconducting quasiparticles ...... 57
3.2 Superconducting state symmetry and impurity states ........ 58
3.3 Localized states from perturbation of pairing potential ... 67
3.4 Extended impurity centers in rf-wave planar systems ....... 72
3.5 Magnetic effect from non-magnetic impurities .............. 78
3.6 Concluding remarks ........................................ 85
Chapter 4 METALLIZATION AND s-WAVE SUPERCONDUCTING ORDER ...... 86
4.1 Physical description of doping process .................... 87
4.2 Doping dependent superconductivity in uniform system ...... 89
4.1 Pairing vs impurity scattering ............................ 92
4.4 Phase diagram of doping vs scattering ..................... 95
4.5 Concluding remarks ........................................ 97
Chapter 5 d-WAVE SUPERCONDUCTING ORDER IN DOPED METALS ........ 98
5.1 Uniform d-wave state ...................................... 99
5.2 Density of states in self-consistent approach ............ 100
5.3 Validity of self-consistent description .................. 107
5.4 Concluding remarks ....................................... 110
Chapter 6 DOPING AND IMPURITY EFFECTS ON d-WAVE
SUPERCONDUCTORS ............................................... 111
6.1 Chemical potential and gap equation ...................... 112
6.2 Impurity effect on the gap parameter ..................... 115
6.3 Non-uniform effects in local d-wave superconducting
order .................................................... 117
6.4 Impurities and suppression of the order parameter ........ 125
6.5 Concluding remarks ....................................... 127
Chapter 7 IMPURITY EFFECTS IN SUPERCONDUCTING
FERROPNICTIDES ................................................ 128
7.1 Specifics of superconducting state in ferropnictide
compounds ................................................ 128
7.2 Impurity in-gap states and in-gap quasiparticle bands .... 130
7.3 Spectral and thermodynamical effects by impurity bands ... 139
7.4 Impurity effects on transport in superconducting
ferropnictides ........................................... 141
7.5 Concluding remarks ....................................... 148
Chapter 8 EFFECTS OF IMPURITY CLUSTERS IN SUPERCONDUCTING
SYSTEMS ....................................................... 150
8.1 Group expansions in superconductors with impurities ...... 150
8.2 Impurity clusters on s-wave density of states ............ 151
8.3 Impurity clusters on d-wave density of states ............ 159
8.4 Convergence of group expansions: extended s-wave ......... 163
8.5 Concluding remarks ....................................... 168
RESUMING CONCLUSIONS .......................................... 169
BIBLIOGRAPHY .................................................. 173
INDEX ......................................................... 178
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