History of Superconductivity: Conventional-, High-Transition Temperature and Novel Superconductors

Since its discovery by H. Kamerling Onnes in Leiden [1] almost one hundred years ago, superconductivity has remained an important area of solid state physics with continuing surprises. Its first observation in Hg, illustrated for historical reasons in Fig

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1.1

Introduction

Since its discovery by H. Kamerling Onnes in Leiden [1] almost one hundred years ago, superconductivity has remained an important area of solid state physics with continuing surprises. Its first observation in Hg, illustrated for historical reasons in Fig. 1.1, resulted from general advances in low temperature physics (liquefying He). The important continuing discovery of new

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Fig. 1.1. Illustration of Kamerling Onnes discovery of superconductivity, vanishing of the electrical resistivity p, in 1911

K. H. Bennemann et al. (eds.), The Physics of Superconductors © Springer-Verlag Berlin Heidelberg 2003

2

K.H. Bennemann, J .B . Ketterson

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Fig. 1.2. Overview of superconducting metals in the periodic table. Note, the absence of superconductivity in the ferromagnetic transition metals and Rare- Earth and Actinide metals

superconductors resulted from advances in material science physics. By 1980 superconductivity has been observed in many metals and alloys thereof. For illustration see Fig. 1.2 [2]. Remarkably, the classical ferromagnets like Ni, Fe, etc. did not exhibit superconductivity. Only for the non- magnetic state and under (strong) pressure has superconductivity been reported (for example in iron, Te = 2K) [3]. From the beginning a strong motivation was to find superconductors with a high transition temperature Te. However, until about 1980 the A-15 compound Nb 3 Ge remained the superconductor with the highest Tc at about 30 K, see Fig. 1.3. In order to achieve higher Te values also many alloys and the effect of applying pressure were studied. Soon after 1980 exciting new superconductors belonging to rather different material classes were discovered. The situation including the high Tc cuprate superconductors discovered by Bednorz and Muller [4] in 1986 is illustrated in Fig. 1.4. For several reasons this stimulated tremendously the minds of the physics community. High- Tc cuprate superconductivity exhibited puzzling new behavior. Perhaps, this helped the birth of new surprises which were yet to come. Hence, one may note that the history of superconductivity exhibits similar alternating periods of great excitement and phases which were more quiet as was the case for other important classical problems in physics. Generally, the study of superconductivity was a motor for new experimental techniques

1

History and Overview

3

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1910 1920 1930

1940

1950

1960

1970

1980 time

Fig. 1.3. History of the transition temperature Tc for the first 70 years following the discovery of superconductivity in 1911. The A-15 compounds were of particular interest in the search for higher Tc- superconductors

as well as for methods in theoretical physics, in many- body physics, and quantum field theory, and is responsible for new concepts of quite general signif