Nobel Laureates in Superconductivity
1913 Nobel Prize
In 1913, Heike Kamerlingh Onnes received the Nobel Prize in Physics "for his investigations on the properties of matter at low temperatures, which led, inter alia, to the production of liquid He4", and the discovery of superconductivity.
In 1908, Kamerlingh Onnes successfully liquefied helium. This allowed him to investigate the thermodynamics properties of helium in the liquid and gas phase. He also investigated the electrical properties of metals down to about 1K. In 1911, he observed the transition to a "zero resistance state" in a pure mercury sample as the temperature of the sample was lowered to below 4.2K. He labeled this "zero resistance state" as "superconductivity."
1962 Nobel Prize
In 1962, Lev Davidovich Landau received the Nobel Prize in Physics "for his pioneering theories for condensed matter, specially liquid helium."
In 1937, Landau proposed a theory of phase transitions, in which he introduced a main variable called the "order parameter", which was finite below the transition and zero above it. This theory has been applied to ferromagnetic, superfluid and superconducting transitions, among others. Different phase transitions have different order parameters. For superfluid helium (see 1978 Nobel Prize), Landau started by considering the state of the fluid at absolute zero as the ground state. The excited states were the quasi particles (see 1972 Nobel Prize), whose dispersion relations were determined in 1957 by neutron scattering measurements at the Atomic Energy Ltd. in Stockholm.
1972 Nobel Prize
In 1972, John Bardeen, Leon N. Cooper and J. Robert Schrieffer received the Nobel Prize in Physics "for the jointly developed theory of superconductivity, usually called the BCS theory."
In 1957, Bardeen, Cooper, and Schrieffer developed a microscopic theory of superconductivity in which pairs of electrons with anti-parallel spins and opposite momenta, known as Cooper pairs, are attracted to each other via the exchange of lattice vibrations, phonons. When the energy of the many body system comprising these Cooper Pairs is computed, they found that a temperature dependent energy gap is produced at the Fermi surface of a material that becomes superconducting. Since Cooper pairs have a spatial extent of 10-4 cm., they cannot be considered non-interacting zero spin particles, Bosons. Therefore, a quasi particle formalism proposed independently by both N. N. Bogoliubov and by J. G. Valatin is used to describe both the electromagnetic and thermodynamic properties of superconductors. In this treatment, excited quasi particles are principally responsible for superconducting thermodynamic properties and their temperature dependences, while quasi particle pairs in the ground state do not interact with the lattice and are principally responsible for the superconducting transport properties
1973 Nobel Prize
In 1973, Leo Esaki, and Ivar Giaever received one quarter each of the Nobel Prize in Physics "for their experimental discoveries regarding tunneling phenomena in semiconductors and superconductors, respectively"; and, Brian David Josephson received one half of the Nobel Prize in Physics "for his theoretical predictions of the properties of a supercurrent through a tunnel barrier, in particular those phenomena which are generally known as the Josephson Effects.
In 1958, Esaki "performed some deceptively simple experiments, which gave convincing evidence for tunneling of electrons in solids." These measurements could be used to determine the energy gap of semiconductors and to scrutinize their electronic states; and, also, to investigate the interaction of tunneling electrons with phonons, photons, plasmons and vibrational modes of the molecular species in the tunneling barriers. These studies led to development of the tunnel diode or the Esaki Diode.
In 1960, Giaever studied the tunneling of electrons, quasi particle excitations, through a "thin sandwich of evaporated metal films insulated by the natural oxide of the film first evaporated", where one or both of the metallic films were superconducting. Thus, he was able to measure the superconducting energy gap from the current versus voltage curves across these tunneling junctions, and also, the density of the phonon states in the superconductor by taking the derivative of these curves.
In 1962, Josephson developed a theory that predicted that under certain experimental conditions, ground state quasi particle pairs, Cooper Pairs, could tunnel through a barrier even when no voltage is applied. This is known as the DC Josephson Effect. Josephson also proposed that, if a voltage could be applied across the junction, an alternating current would flow across the junction with the ratio of frequency to applied voltage being a multiple of the quantity h/2e, which is called the magnetic flux quantum, where h is Planck's constant and e is the charge of the electron. This is called the "AC Josephson Effect", which has been used to define the International Voltage Standard
1978 Nobel Prize
In 1978, Pyotr Leonidovich Kapitsa received one half of the Nobel Prize in Physics "for his basic inventions and discoveries in the area of low temperature physics," which included the discovery of superfluidity in He. The other half of the Nobel Prize in 1978 was awarded to Arno Allen Penzias and Robert Woodrow Wilson "for their discovery of cosmic microwave background radiation."
Starting in 1921, while working with Ernest Rutherford at the Cavendish Laboratory, Cambridge University, Kapitsa "made the first experiment in which a cloud chamber was placed in a strong magnetic field and observed the bending of alpha-particle paths." In 1924, he developed methods for producing magnetic fields as high as half a Megagauss, which were not surpassed in strength until 1956, which he used to discover the linear dependence of the resistivity of various metals in strong magnetic fields.
In 1932, the Royal Society Mond Laboratory was created specially for Kapitsa. By 1934, he had developed there "an ingenious (adiabatic expansion) device for liquefying helium in large quantities - a pre-requisite for the great progress made in low temperature physics…."
Kapitsa returned to Russia in 1934 and was detained there. He was made director of the Institute of Physical Problems of the Soviet Academy of Sciences in Moscow. Through the intercession of Rutherford, Kapitza was permitted to have the equipment from the Mond Laboratory shipped to Moscow. While investigating the heat conduction properties of helium, he discovered "the superfluidity of (liquid) helium, implying that the internal friction (viscosity) of the fluid disappears below 2.2K (the so called lambda-point of helium)……Kapitsa stands out as one of the greatest experimentalists of our time (1978), in his domain the uncontested pioneer, leader and master."
1987 Nobel Prize
In 1987, J. Georg Bednorz and K. Alexander Müller received the Nobel Prize in Physics "for their important breakthrough in the discovery of superconductivity in ceramic materials."
In 1986, Bednorz and Müller synthesized a ceramic material consisting of lanthanum-barium-copper-oxide in carefully determined ratios which underwent an abrupt transition to "zero" resistance at a temperature near 35K, which was subsequently shown to exhibit all the properties of a superconductor - including the Meissner Effect. This transition temperature was about 50% higher than the then highest known value of 23K found in a Nb3Ge film that was first synthesized by John Gavaler in 1973.
The Bednorz and Müller collaboration had started in 1983 when they initiated a program to search for superconductivity in oxides. They began by investigating oxide systems which exhibited a large Jahn-Teller effect, La-Ni-O, then replacing some Ni by aluminum and later by copper. Although these oxides showed promising behavior they did not exhibit superconductivity. In late 1985 stimulated by the work of French scientists on the catalytic properties of Ba-La-Cu oxides with a Perovskite structure which exhibited metallic properties, they synthesized a series of solid state solutions - varying the Ba/La ratio and then measuring their temperature dependent resistance down to liquid helium temperatures.
By this careful work imbued with innate insight, they finally managed to prepare the superconducting ceramic mentioned above with a Tc of 35K. Stimulated by their published results of superconductivity at 35K, scientists world wide began
investigating these and other oxide systems which soon achieved Tc 's exceeding 100K.
1996 Nobel Prize
In 1996, David M. Lee, Douglas D. Osheroff and Robert C. Richardson received the Nobel Prize in Physics "for their discovery of superfluidity in helium-3."
In 1972, Lee, Osheroff and Richardson discovered superfluid 3He. Both 3He and superconductors are composed of Fermi particles. The ground state of both may be described as a Bose-Einstein condensed pair. The bound Cooper pairs of anti parallel spins in a superconductor have a net spin of zero. Lee, Osheroff and Richardson were able to show that the ground state of the paired 3He nuclei exhibits a net spin of 1 and, in addition, the pair has an orbital angular momentum of 1.
2003 Nobel Prize
In 2003, Alexei A. Abrikosov, Vitaly L. Ginsburg and Anthony J. Leggett received the Nobel Prize in Physics "for pioneering contributions to the theory of superconductors and superfluids.
In 1950, Ginzburg and Lev Landau published a phenomelogical theory for superconductivity, wherein the order parameter introduced by Landau to describe phase transitions is identified as a scalar complex wave function.
According to this theory, the properties of superconductors depend on a dimensionless material constant - now known as the Ginzburg-Landau constant, κ, which is proportional to the ratio of the London penetration depth λ to the coherence length δ, = λ/δ. Here, λ is the distance that a magnetic field penetrates a superconductor, and δ is a length within which the order parameter cannot change appreciably. If κ < , the surface energy of the interface between a normal material and its superconducting phase is positive; and, if κ > , then it is negative.
In a Type II superconductor, the magnetic field starts to penetrate a bulk superconductor at a lower critical field, Hc1, which is proportional to Hc/κ. Superconductivity disappears at the upper critical field, Hc2, which is proportional to κHc. Superconductivity and magnetism coexist in the mixed phase between Hc1 and Hc2. The magnetic field penetrates the superconductor in the form flux quanta first introduced by Fritz London in 1950.
In 1954, Alexei Abrikosov studied the magnetic properties of superconducting films in these two limits, and came to the conclusion that there existed two types of superconductors, Type I with positive surface energy and Type II with negative surface energy. In 1957, Abrikosov investigated theoretically the properties of bulk Type II superconductors. He found that in a Type II superconductor the transition to the normal state in a magnetic field is a second order phase transition, as opposed to a Type I superconductor, which is perfectly diamagnetic in the superconducting state and where the magnetic transition is first order. The threshold or critical value of the magnetic field that will destroy superconductivity is called Hc in a Type I superconductor.
In a Type II superconductor, the magnetic field starts to penetrate a bulk superconductor at a lower critical field, Hc, which is proportional to Hc/κ. Superconductivity disappears at the upper critical field, Hc2, which is proportional to κHc. Superconductivity and magnetism coexist in the mixed phase between Hc1 and Hc2. The magnetic field penetrates the superconductor in the form of flux quanta first introduced by Fritz London in 1950.
Initially, Abrikosov postulated that the flux lines in a superconductor arrange themselves in a square lattice. It was later determined that a lower energy state is achieved if they are ordered in a triangular lattice. Most of the superconductors discovered or synthesized since 1960 have been Type II superconductors. The work of Abrikosov contributed significantly to the study of these novel superconducting materials.
In 1972, Leggett proposed a theory for superfluid 3He which "succeeded in explaining the relationship between its properties and the many types of order associated with an order parameter that has eighteen components" because it is composed both of spin angular momentum and orbital angular momentum. "His theory helped experimentalist to interpret their measurements and provided a framework for systematic investigations. Leggett's theory has also been used in other fields, as divers as liquid crystal physics and cosmology."
The quotations included in the description of the Nobel Prizes are taken from the Nobel Prize Announcements, presentations, biographies and Nobel Laureate lectures.