New Superconductors : From Granular to High Tc

by Deutscher, Guy

• ISBN13: 9789810230890
• ISBN10: 9810230893
• Format: Hardcover
• Copyright: 2006-09-30
• Publisher: World Scientific Pub Co Inc

Summary

How new are the high Tc superconductors, as compared to the conventional low Tc ones? In what sense are these oxides different from regular metals in their normal state? How different is the mechanism for high Tc superconductivity from the well-known electron-phonon interaction that explains so well superconductivity in metals and alloys? What are the implications of the new features of the high Tc oxides for their practical applications? This highly interesting book aims to give some answers to those questions, drawing particularly on similarities between the high Tc oxides and granular superconductors, which also present a maximum of their critical temperature near the metal-insulator transition.

Table of Contents

1 Superfluidity	1	(20)
1.1 The Landau critical velocity	1	(3)
1.2 Origin of the condensate	4	(4)
1.3 Phase of the condensate	8	(2)
1.4 Two-Fermion superfluids	10	(6)
1.4.1 The Meissner effect	13	(1)
1.4.2 Flux quantization	14	(2)
1.5 BCS superconducting metals	16	(3)
1.5.1 Condensation energy	16	(1)
1.5.2 The BCS wave function	17	(2)
1.6 Summary	19	(1)
1.7 Further reading	20	(1)
2 Coherence length, penetration depth and critical temperature	21	(22)
2.1 Origin of the coherence length in superconducting metals	22	(3)
2.2 Experimental methods for the determination of the coherence length	25	(7)
2.2.1 Boundary effect	26	(2)
2.2.2 Nucleation field	28	(1)
2.2.3 Nucleation field and thermodynamical critical field	29	(2)
2.2.4 Surface nucleation	31	(1)
2.3 Experimental results for the coherence length	32	(5)
2.3.1 Boundary effect experiments	32	(1)
2.3.2 Nucleation field measurements	32	(3)
2.3.3 Comparison with theoretical predictions	35	(2)
2.4 Penetration depth and critical temperature	37	(3)
2.4.1 The Uemura law	37	(1)
2.4.2 Granular superconductors	38	(2)
2.5 Further reading	40	(3)
3 The phase transition	43	(20)
3.1 Free energies	43	(7)
3.1.1 Metals: mean field behavior	45	(1)
3.1.2 Examples of non-mean field behavior	46	(1)
3.1.3 The anomalous normal state in the ceramics	47	(3)
3.2 Fluctuations	50	(10)
3.2.1 The small grain case	50	(3)
3.2.2 Three-dimensional fluctuations: quasi-mean field treatment	53	(2)
3.2.3 The heat capacity transition in the High Tc: the case of YBCO	55	(4)
3.2.4 The heat capacity transition in high anisotropy cuprates	59	(1)
3.3 Condensation energies	60	(1)
3.4 Summary	61	(1)
3.5 Further reading	62	(1)
4 Phase diagrams	63	(28)
4.1 Granular superconductors	65	(16)
4.1.1 The granular structure	66	(2)
4.1.2 The M/I transition in the granular structure: progressive Coulomb blockade	68	(1)
4.1.3 Transport regimes and the phase diagram	69	(7)
4.1.4 Loss of superfluid density and decrease of Tc near the M/I transition	76	(2)
4.1.5 The short coherence length of granular superconductors	78	(3)
4.2 Phase diagram of the cuprates	81	(8)
4.2.1 Transport regimes and the phase diagram	84	(3)
4.2.2 Loss of superfluid density and critical temperature in the cuprates	87	(2)
4.3 Summary	89	(1)
4.4 Further reading	89	(2)
5 Gap, symmetry and pseudo-gap	91	(26)
5.1 The BCS s-wave gap	92	(7)
5.1.1 The BCS density of states	92	(2)
5.1.2 Giaever tunneling and Andreev-Saint-James reflections	94	(5)
5.2 Gap symmetry in the cuprates	99	(12)
5.2.1 Experimental evidence for low lying states	99	(2)
5.2.2 Gap anisotropy	101	(10)
5.3 Superconducting gap and pseudo-gap	111	(3)
5.4 Summary	114	(1)
5.5 Further reading	115	(2)
6 Basics on vortices	117	(18)
6.1 Vortices and vortex matter	117	(1)
6.2 The isolated vortex	118	(3)
6.2.1 The line energy	118	(2)
6.2.2 Vortex rigidity and pinning	120	(1)
6.3 Formation of the vortex lattice	121	(6)
6.3.1 Field of first entry: equilibrium	122	(1)
6.3.2 Field of first entry: Bean-Livingston barrier	122	(1)
6.3.3 Vortex interactions and lattice formation	123	(2)
6.3.4 Lattice deformations	125	(1)
6.3.5 The Abrikosov lattice near Hc2	126	(1)
6.4 Vortex motion	127	(3)
6.5 Probing surface currents in d-wave superconductors	130	(3)
6.6 Summary	133	(1)
6.7 Further reading	133	(2)
7 Cuprate superconductors under strong fields	135	(20)
7.1 Vortex lattice melting	136	(7)
7.1.1 Lattice melting — Lindemann criterion	137	(2)
7.1.2 Melting and order parameter fluctuation effects	139	(2)
7.1.3 Loss of line tension	141	(2)
7.1.4 Effect of disorder on vortex phase transitions	143	(1)
7.2 Experiments on vortex phase transitions	143	(10)
7.2.1 Experimental methods	143	(4)
7.2.2 Vortex phase transitions in Bi 2212 crystals	147	(2)
7.2.3 Vortex phase transitions in YBCO crystals	149	(4)
7.3 Summary	153	(1)
7.4 Further reading	153	(2)
8 From fundamentals to applications	155	(34)
8.1 The need for high critical temperatures and fields	155	(3)
8.2 High critical temperatures	158	(16)
8.2.1 BCS theory	158	(1)
8.2.2 The McMillan strong coupling extension of the BCS theory	159	(1)
8.2.3 Density of states effects	160	(3)
8.2.4 The BCS to Bose–Einstein strong coupling cross-over	163	(6)
8.2.5 Unconventional pairing mechanisms	169	(3)
8.2.6 Is there a BCS to BE cross-over in the cuprates?	172	(1)
8.2.7 Critical currents in weak fields: the depairing limit	173	(1)
8.3 Upper critical fields	174	(3)
8.3.1 Zero temperature limit	174	(3)
8.4 Practical upper temperature for superconductivity	177	(9)
8.4.1 Role of the condensation energy	177	(4)
8.4.2 Loss of line tension	181	(4)
8.4.3 Concluding remarks: coupling strength versus useful high Tc	185	(1)
8.5 Further reading	186	(3)
9 HTS conductors and their applications	189	(30)
9.1 Grain boundaries	191	(5)
9.2 First and second generation wires	196	(22)
9.2.1 Properties of first generation wires	197	(2)
9.2.2 Applications of 1G wire	199	(5)
9.2.3 Progress in coated conductors: 2G wire	204	(4)
9.2.4 Coated conductor performance	208	(10)
9.3 Further reading	218	(1)
Index	219