Theory Of Superconductivity

J. Robert Schrieffer

• Publisher: CRC Press
• Year: 2018
• Print ISBN: 9781138330009
• eBook ISBN: 9780429975332
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Physics
• Index: Physics

Theory of Superconductivity is primarily intended to serve as a background for reading the literature in which detailed applications of the microscopic theory of superconductivity are made to specific problems.

CHAPTER 1

INTRODUCTION

The phenomenon of superconductivity is a remarkable example of quantum effects operating on a truly macroscopic scale.¹ In a superconducting material, a finite fraction of the electrons are in a real sense condensed into a “macromolecule” (or “superfluid”) which extends over the entire volume of the system and is capable of motion as a whole. At zero temperature the condensation is complete and all the electrons participate in forming this superfluid, although only those electrons near the Fermi surface have their motion appreciably affected by the condensation. As the temperature is increased, a fraction of the electrons evaporate from the condensate and form a weakly interacting gas of excitations (or “normal fluid”), which also extends throughout the entire volume of the system, interpenetrating the superfluid.² As the temperature approaches a critical value T_c, the fraction of electrons remaining in the superfluid tends to zero and the system undergoes a second-order phase transition from the superconducting to the normal state. This two-fluid picture of a superconductor is formally analogous to that which characterizes superfluid He⁴, although there are important differences between these systems.^1,3

The amazing properties of superconductors (e.g., perfect diamagnetism, zero d-c electrical resistance, etc.⁴) are related to the peculiar excitation spectrum of the superfluid. As we shall see, the superfluid can carry out potential (or irrotational) flow with little change of its “internal energy” (i.e., energy associated with forces binding the superfluid together). On the other hand, the superfluid cannot support rotational flow. In analogy with superfluid He⁴, if one tries to force the superfluid into motion having vorticity (i.e., a nonvanishing curl of its linear momentum), a fraction of the superfluid is necessarily converted into normal fluid. Since the normal fluid does not take advantage of the forces binding the superfluid together, there is in general a large increase in energy associated with creating this vorticity. It is reasonable, therefore, that the superfluid possesses a rigidity or stiffness with respect to perturbations which, like the magnetic field, tends to impart vorticity (i.e., angular momentum) to the system. On the basis of this assumed rigidity, London^1,5 was able to account theoretically for the perfect diamagnetism of bulk superconductors in weak magnetic fields (the Meissner effect⁶) and for the apparent lack of d-c electrical resistance, as first observed by Kamerlingh Onnes in 1911.⁷

As we shall see...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Preface to the Revised Printing
• CHAPTER 1 INTRODUCTION
• CHAPTER 2 THE PAIRING THEORY OF SUPERCONDUCTIVITY
• CHAPTER 3 APPLICATIONS OF THE PAIRING THEORY
• CHAPTER 4 ELECTRON-ION SYSTEM
• CHAPTER 5 FIELD-THEORETIC METHODS IN THE MANY-BODY PROBLEM
• CHAPTER 6 ELEMENTARY EXCITATIONS IN NORMAL METALS
• CHAPTER 7 FIELD-THEORETIC METHODS APPLIED TO SUPERCONDUCTIVITY
• CHAPTER 8 ELECTROMAGNETIC PROPERTIES OF SUPERCONDUCTORS
• CONCLUSION
• APPENDIX SECOND QUANTIZATION FORMALISM
• APPENDIX NOBEL LECTURES, 1972
• NOTES AND REFERENCES
• INDEX