History of superconductivity
Encyclopedia
The history of superconductivity, the property exhibited by certain substances of lacking electrical resistance
at temperatures close to absolute zero
, began at the end of the 19th century and culminated in Heike Kamerlingh Onnes
's 1911 discovery. The theory surrounding the property of superconductivity
was further developed over the course of the 20th century.
initiated research into electrical resistance at low-temperatures. Zygmunt Florenty Wroblewski
conducted research into the electrical properties at low temperatures, though his research ended early due to his accidental death. Around 1864, Karol Olszewski
and Wroblewski predicted the electrical phenomena in ultra-cold temperatures of dropping resistance levels. Olszewski and Wroblewski documented evidence of this in the 1880s.
Dewar and John Ambrose Fleming
predicted that at absolute zero
, pure metals would become perfect electromagnetic conductors (though, later, Dewar altered his opinion on the disappearance of resistance believing that there would always be some resistance). Walther Hermann Nernst
developed the third law of thermodynamics
and stated that absolute zero was unattainable. Carl von Linde
and William Hampson, both commercial researchers, nearly at the same time filed for patents on the Joule-Thomson effect
. Linde's patent was the climax of 20 years of systematic investigation of established facts, using a regenerative counterflow method. Hampson's designs was also of a regenerative method. The combined process became known as the Linde-Hampson liquefaction process.
Onnes purchased a Linde machine for his research. On March 21, 1900, Nikola Tesla
was granted a US patent for the means for increasing the intensity of electrical oscillation
s by lowering temperature, which was caused by lowered resistance, a phenomenon previously observed by Olszewski and Wroblewski. Within this patent it describes the increase intensity and duration of electric oscillations of a low temperature
resonating
circuit. It is believed that Tesla had intended that Linde's machine would be used to attain the cooling agents.
A milestone was achieved on 10 July 1908 when Heike Kamerlingh Onnes
at the Leiden University
in Leiden produced, for the first time, liquified helium
.
and Jacob Clay reinvestigated Dewars's earlier experiments on the reduction of resistance at low temperatures. Onnes began the investigations with platinum
and gold, replacing these later with mercury
(a more readily refineable material). Onnes's research into the resistivity of solid mercury at cryogenic temperatures was accomplished by using liquid helium
as a refrigerant. On April 8, 1911, 16:00 hours Onnes noted "Kwik nagenoeg nul", which translates as [Resistance of] mercury almost zero. At the temperature of 4.19 K, he observed that the resistivity abruptly disappeared (the measuring device Onnes was using did not indicate any resistance). Onnes disclosed his research in 1911, in a paper titled "On the Sudden Rate at Which the Resistance of Mercury Disappears". Onnes stated in that paper that the "specific resistance" became thousands of times less in amount relative to the best conductor at ordinary temperature. Onnes later reversed the process and found that at 4.2 K, the resistance returned to the material. The next year, Onnes published more articles about the phenomenon. Initially, Onnes called the phenomenon "supraconductivity" (1913) and, only later, adopted the term "superconductivity". For his research, he was awarded the Nobel Prize in Physics
in 1913.
Onnes conducted an experiment, in 1912, on the usability of superconductivity. Onnes introduced an electrical current into a superconductive ring and removed the battery that generated it. Upon measuring the electrical current, Onnes found that its intensity did not diminish with the time. The current persisted due to the superconductive state of the conductive medium. In subsequent decades, superconductivity was found in several other materials. In 1913, lead was found to superconduct at 7 K, and in 1941 niobium nitride was found to superconduct at 16 K.
discovered that superconductors expelled applied magnetic fields, a phenomenon which has come to be known as the Meissner effect
. In 1935, F.
and H. London
showed that the Meissner effect was a consequence of the minimization of the electromagnetic free energy
carried by superconducting current. In 1950, the phenomenological Ginzburg-Landau theory
of superconductivity was devised by Landau and Ginzburg.
The Ginzburg-Landau theory, which combined Landau's theory of second-order phase transition
s with a Schrödinger
-like wave equation, had great success in explaining the macroscopic properties of superconductors. In particular, Abrikosov showed that Ginzburg-Landau theory predicts the division of superconductors into the two categories now referred to as Type I and Type II. Abrikosov and Ginzburg were awarded the 2003 Nobel Prize for their work (Landau having died in 1968). Also in 1950, Maxwell and Reynolds et al. found that the critical temperature of a superconductor depends on the isotopic mass
of the constituent element
. This important discovery pointed to the electron-phonon interaction as the microscopic mechanism responsible for superconductivity.
, Cooper, and Schrieffer
. This BCS theory
explained the superconducting current as a superfluid of Cooper pair
s, pairs of electrons interacting through the exchange of phonons. For this work, the authors were awarded the Nobel Prize in 1972. The BCS theory was set on a firmer footing in 1958, when Bogoliubov
showed that the BCS wavefunction, which had originally been derived from a variational argument, could be obtained using a canonical transformation of the electronic Hamiltonian
. In 1959, Lev Gor'kov
showed that the BCS theory reduced to the Ginzburg-Landau theory close to the critical temperature. Gor'kov was the first to derive the superconducting phase evolution equation
.
s subjected to a parallel magnetic field
. The electrical resistance
of such cylinders shows a periodic oscillation
with the magnetic flux piercing the cylinder, the period being h
/2e
= 2.07×10−15 V·s. The explanation provided by Little and Parks is that the resistance oscillation reflects a more fundamental phenomenon, i.e. periodic oscillation of the superconducting critical temperature (Tc). This is the temperature at which the sample becomes superconducting. The LP effect is a result of collective quantum behavior of superconducting electrons. It reflects the general fact that it is the fluxoid rather than the flux which is quantized in superconductors. The LP effect demonstrates that vector-potential couples to an observable physical quantity, namely the superconducting critical temperature.
alloy, was developed by researchers at Westinghouse.
In the same year, Josephson
made the important theoretical prediction that a supercurrent can flow between two pieces of superconductor separated by a thin layer of insulator. This phenomenon, now called the Josephson effect
, is exploited by superconducting devices such as SQUID
s. It is used in the most accurate available measurements of the magnetic flux quantum
h/2e, and thus (coupled with the quantum Hall resistivity) for Planck's constant h. Josephson was awarded the Nobel Prize for this work in 1973.
In 1973 found to have Tc of 23 K which remained the highest ambient-pressure Tc until the discovery of the cuprate high temperature superconductors in 1986 (see below).
and Mueller
discovered superconductivity in a lanthanum
-based cuprate perovskite
material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987) and was the first of the high temperature superconductors. It was shortly found (by Ching-Wu Chu) that replacing the lanthanum with yttrium
, i.e. making YBCO, raised the critical temperature to 92 K, which was important because liquid nitrogen
could then be used as a refrigerant (at atmospheric pressure, the boiling point of nitrogen is 77 K.) This is important commercially because liquid nitrogen can be produced cheaply on-site with no raw materials, and is not prone to some of the problems (solid air plugs, etc.) of helium in piping. Many other cuprate superconductors have since been discovered, and the theory of superconductivity in these materials is one of the major outstanding challenges of theoretical condensed matter physics
.
In March 2001 superconductivity of Magnesium diboride
was found with Tc of 39 K.
In 2008 the oxypnictide
or iron-based superconductor
s were discovered which led to a flurry of work in the hope that studying them would provide a theory of the cuprate superconductors.
BCS theory
Other papers
Other books
Patents
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
at temperatures close to absolute zero
Absolute zero
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means....
, began at the end of the 19th century and culminated in Heike Kamerlingh Onnes
Heike Kamerlingh Onnes
Heike Kamerlingh Onnes was a Dutch physicist and Nobel laureate. He pioneered refrigeration techniques, and he explored how materials behaved when cooled to nearly absolute zero. He was the first to liquify helium...
's 1911 discovery. The theory surrounding the property of superconductivity
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...
was further developed over the course of the 20th century.
Exploring ultra-cold phenomena (to 1908)
James DewarJames Dewar
Sir James Dewar FRS was a Scottish chemist and physicist. He is probably best-known today for his invention of the Dewar flask, which he used in conjunction with extensive research into the liquefaction of gases...
initiated research into electrical resistance at low-temperatures. Zygmunt Florenty Wroblewski
Zygmunt Florenty Wróblewski
Zygmunt Florenty Wróblewski was a Polish physicist and chemist.-Life:Wróblewski was born in Grodno . He studied at Kiev University. After a six-year exile for participating in the January 1863 Uprising against Imperial Russia, he studied in Berlin and Heidelberg...
conducted research into the electrical properties at low temperatures, though his research ended early due to his accidental death. Around 1864, Karol Olszewski
Karol Olszewski
Karol Stanisław Olszewski was a Polish chemist, mathematician and physicist.-Life:Olszewski was a graduate of Kazimierz Brodziński High School in Tarnów . He studied at Kraków's Jagiellonian University in the departments of mathematics and physics, and chemistry and biology...
and Wroblewski predicted the electrical phenomena in ultra-cold temperatures of dropping resistance levels. Olszewski and Wroblewski documented evidence of this in the 1880s.
Dewar and John Ambrose Fleming
John Ambrose Fleming
Sir John Ambrose Fleming was an English electrical engineer and physicist. He is known for inventing the first thermionic valve or vacuum tube, the diode, then called the kenotron in 1904. He is also famous for the left hand rule...
predicted that at absolute zero
Absolute zero
Absolute zero is the theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached using only thermodynamic means....
, pure metals would become perfect electromagnetic conductors (though, later, Dewar altered his opinion on the disappearance of resistance believing that there would always be some resistance). Walther Hermann Nernst
Walther Nernst
Walther Hermann Nernst FRS was a German physical chemist and physicist who is known for his theories behind the calculation of chemical affinity as embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize in chemistry...
developed the third law of thermodynamics
Third law of thermodynamics
The third law of thermodynamics is a statistical law of nature regarding entropy:For other materials, the residual entropy is not necessarily zero, although it is always zero for a perfect crystal in which there is only one possible ground state.-History:...
and stated that absolute zero was unattainable. Carl von Linde
Carl von Linde
Professor Doctor Carl Paul Gottfried von Linde was a German engineer who developed refrigeration and gas separation technologies...
and William Hampson, both commercial researchers, nearly at the same time filed for patents on the Joule-Thomson effect
Joule-Thomson effect
In thermodynamics, the Joule–Thomson effect or Joule–Kelvin effect or Kelvin–Joule effect describes the temperature change of a gas or liquid when it is forced through a valve or porous plug while kept insulated so that no heat is exchanged with the environment. This procedure is called a...
. Linde's patent was the climax of 20 years of systematic investigation of established facts, using a regenerative counterflow method. Hampson's designs was also of a regenerative method. The combined process became known as the Linde-Hampson liquefaction process.
Onnes purchased a Linde machine for his research. On March 21, 1900, Nikola Tesla
Nikola Tesla
Nikola Tesla was a Serbian-American inventor, mechanical engineer, and electrical engineer...
was granted a US patent for the means for increasing the intensity of electrical oscillation
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
s by lowering temperature, which was caused by lowered resistance, a phenomenon previously observed by Olszewski and Wroblewski. Within this patent it describes the increase intensity and duration of electric oscillations of a low temperature
Cryogenics
In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. A person who studies elements under extremely cold temperature is called a cryogenicist. Rather than the relative temperature scales of Celsius and Fahrenheit,...
resonating
Resonator
A resonator is a device or system that exhibits resonance or resonant behavior, that is, it naturally oscillates at some frequencies, called its resonant frequencies, with greater amplitude than at others. The oscillations in a resonator can be either electromagnetic or mechanical...
circuit. It is believed that Tesla had intended that Linde's machine would be used to attain the cooling agents.
A milestone was achieved on 10 July 1908 when Heike Kamerlingh Onnes
Heike Kamerlingh Onnes
Heike Kamerlingh Onnes was a Dutch physicist and Nobel laureate. He pioneered refrigeration techniques, and he explored how materials behaved when cooled to nearly absolute zero. He was the first to liquify helium...
at the Leiden University
Leiden University
Leiden University , located in the city of Leiden, is the oldest university in the Netherlands. The university was founded in 1575 by William, Prince of Orange, leader of the Dutch Revolt in the Eighty Years' War. The royal Dutch House of Orange-Nassau and Leiden University still have a close...
in Leiden produced, for the first time, liquified helium
Liquid helium
Helium exists in liquid form only at extremely low temperatures. The boiling point and critical point depend on the isotope of the helium; see the table below for values. The density of liquid helium-4 at its boiling point and 1 atmosphere is approximately 0.125 g/mL Helium-4 was first liquefied...
.
Sudden and fundamental disappearance
Heike Kamerlingh OnnesHeike Kamerlingh Onnes
Heike Kamerlingh Onnes was a Dutch physicist and Nobel laureate. He pioneered refrigeration techniques, and he explored how materials behaved when cooled to nearly absolute zero. He was the first to liquify helium...
and Jacob Clay reinvestigated Dewars's earlier experiments on the reduction of resistance at low temperatures. Onnes began the investigations with platinum
Platinum
Platinum is a chemical element with the chemical symbol Pt and an atomic number of 78. Its name is derived from the Spanish term platina del Pinto, which is literally translated into "little silver of the Pinto River." It is a dense, malleable, ductile, precious, gray-white transition metal...
and gold, replacing these later with mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
(a more readily refineable material). Onnes's research into the resistivity of solid mercury at cryogenic temperatures was accomplished by using liquid helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
as a refrigerant. On April 8, 1911, 16:00 hours Onnes noted "Kwik nagenoeg nul", which translates as [Resistance of] mercury almost zero. At the temperature of 4.19 K, he observed that the resistivity abruptly disappeared (the measuring device Onnes was using did not indicate any resistance). Onnes disclosed his research in 1911, in a paper titled "On the Sudden Rate at Which the Resistance of Mercury Disappears". Onnes stated in that paper that the "specific resistance" became thousands of times less in amount relative to the best conductor at ordinary temperature. Onnes later reversed the process and found that at 4.2 K, the resistance returned to the material. The next year, Onnes published more articles about the phenomenon. Initially, Onnes called the phenomenon "supraconductivity" (1913) and, only later, adopted the term "superconductivity". For his research, he was awarded the Nobel Prize in Physics
Nobel Prize in Physics
The Nobel Prize in Physics is awarded once a year by the Royal Swedish Academy of Sciences. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others are the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and...
in 1913.
Onnes conducted an experiment, in 1912, on the usability of superconductivity. Onnes introduced an electrical current into a superconductive ring and removed the battery that generated it. Upon measuring the electrical current, Onnes found that its intensity did not diminish with the time. The current persisted due to the superconductive state of the conductive medium. In subsequent decades, superconductivity was found in several other materials. In 1913, lead was found to superconduct at 7 K, and in 1941 niobium nitride was found to superconduct at 16 K.
Enigmas and solutions (1933–)
The next important step in understanding superconductivity occurred in 1933, when Meissner and OchsenfeldRobert Ochsenfeld
Robert Ochsenfeld was a German physicist born on May 18, 1901 in Hilchenbach . In 1933 he discovered with Walter Meissner the Meißner-Ochsenfeld effect.He died on December 5, 1993 in Hilchenbach....
discovered that superconductors expelled applied magnetic fields, a phenomenon which has come to be known as the Meissner effect
Meissner effect
The Meissner effect is the expulsion of a magnetic field from a superconductor during its transition to the superconducting state. The German physicists Walther Meissner and Robert Ochsenfeld discovered the phenomenon in 1933 by measuring the magnetic field distribution outside superconducting tin...
. In 1935, F.
Fritz London
Fritz Wolfgang London was a German theoretical physicist. His fundamental contributions to the theories of chemical bonding and of intermolecular forces are today considered classic and are discussed in standard textbooks of physical chemistry.With his brother Heinz, he made a significant...
and H. London
Heinz London
Heinz London was a German Physicist. He worked with his brother Fritz on superconductivity, discovering the London equations when working in Oxford, at the Clarendon Laboratory; these equations gave a first explanation to the Meissner effect...
showed that the Meissner effect was a consequence of the minimization of the electromagnetic free energy
Thermodynamic free energy
The thermodynamic free energy is the amount of work that a thermodynamic system can perform. The concept is useful in the thermodynamics of chemical or thermal processes in engineering and science. The free energy is the internal energy of a system less the amount of energy that cannot be used to...
carried by superconducting current. In 1950, the phenomenological Ginzburg-Landau theory
Ginzburg-Landau theory
In physics, Ginzburg–Landau theory, named after Vitaly Lazarevich Ginzburg and Lev Landau, is a mathematical theory used to model superconductivity. It does not purport to explain the microscopic mechanisms giving rise to superconductivity...
of superconductivity was devised by Landau and Ginzburg.
The Ginzburg-Landau theory, which combined Landau's theory of second-order phase transition
Phase transition
A phase transition is the transformation of a thermodynamic system from one phase or state of matter to another.A phase of a thermodynamic system and the states of matter have uniform physical properties....
s with a Schrödinger
Schrödinger equation
The Schrödinger equation was formulated in 1926 by Austrian physicist Erwin Schrödinger. Used in physics , it is an equation that describes how the quantum state of a physical system changes in time....
-like wave equation, had great success in explaining the macroscopic properties of superconductors. In particular, Abrikosov showed that Ginzburg-Landau theory predicts the division of superconductors into the two categories now referred to as Type I and Type II. Abrikosov and Ginzburg were awarded the 2003 Nobel Prize for their work (Landau having died in 1968). Also in 1950, Maxwell and Reynolds et al. found that the critical temperature of a superconductor depends on the isotopic mass
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
of the constituent element
Chemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
. This important discovery pointed to the electron-phonon interaction as the microscopic mechanism responsible for superconductivity.
BCS Theory
The complete microscopic theory of superconductivity was finally proposed in 1957 by BardeenJohn Bardeen
John Bardeen was an American physicist and electrical engineer, the only person to have won the Nobel Prize in Physics twice: first in 1956 with William Shockley and Walter Brattain for the invention of the transistor; and again in 1972 with Leon Neil Cooper and John Robert Schrieffer for a...
, Cooper, and Schrieffer
John Robert Schrieffer
John Robert Schrieffer is an American physicist and, with John Bardeen and Leon N Cooper, recipient of the 1972 Nobel Prize for Physics for developing the BCS theory, the first successful microscopic theory of superconductivity.-Biography:...
. This BCS theory
BCS theory
BCS theory — proposed by Bardeen, Cooper, and Schrieffer in 1957 — is the first microscopic theory of superconductivity since its discovery in 1911. The theory describes superconductivity as a microscopic effect caused by a "condensation" of pairs of electrons into a boson-like state...
explained the superconducting current as a superfluid of Cooper pair
Cooper pair
In condensed matter physics, a Cooper pair or BCS pair is two electrons that are bound together at low temperatures in a certain manner first described in 1956 by American physicist Leon Cooper...
s, pairs of electrons interacting through the exchange of phonons. For this work, the authors were awarded the Nobel Prize in 1972. The BCS theory was set on a firmer footing in 1958, when Bogoliubov
Nikolay Bogolyubov
Nikolay Nikolaevich Bogolyubov was a Russian and Ukrainian Soviet mathematician and theoretical physicist known for a significant contribution to quantum field theory, classical and quantum statistical mechanics, and to the theory of dynamical systems; a recipient of the Dirac Prize...
showed that the BCS wavefunction, which had originally been derived from a variational argument, could be obtained using a canonical transformation of the electronic Hamiltonian
Hamiltonian (quantum mechanics)
In quantum mechanics, the Hamiltonian H, also Ȟ or Ĥ, is the operator corresponding to the total energy of the system. Its spectrum is the set of possible outcomes when one measures the total energy of a system...
. In 1959, Lev Gor'kov
Lev Gor'kov
Lev Gor'kov is a Soviet-Russian-American research physicist internationally known for his pioneering work in the field of superconductivity.He is a professor of physics at Florida State University in Tallahassee, Florida, and a program director in Condensed Matter at the National High Magnetic...
showed that the BCS theory reduced to the Ginzburg-Landau theory close to the critical temperature. Gor'kov was the first to derive the superconducting phase evolution equation
.Little and Parks effect
The Little-Parks effect was discovered in 1962 in experiments with empty and thin-walled superconducting cylinderCylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
s subjected to a parallel magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
. The electrical resistance
Electrical resistance
The electrical resistance of an electrical element is the opposition to the passage of an electric current through that element; the inverse quantity is electrical conductance, the ease at which an electric current passes. Electrical resistance shares some conceptual parallels with the mechanical...
of such cylinders shows a periodic oscillation
Oscillation
Oscillation is the repetitive variation, typically in time, of some measure about a central value or between two or more different states. Familiar examples include a swinging pendulum and AC power. The term vibration is sometimes used more narrowly to mean a mechanical oscillation but sometimes...
with the magnetic flux piercing the cylinder, the period being h
Planck constant
The Planck constant , also called Planck's constant, is a physical constant reflecting the sizes of energy quanta in quantum mechanics. It is named after Max Planck, one of the founders of quantum theory, who discovered it in 1899...
/2e
Elementary charge
The elementary charge, usually denoted as e, is the electric charge carried by a single proton, or equivalently, the absolute value of the electric charge carried by a single electron. This elementary charge is a fundamental physical constant. To avoid confusion over its sign, e is sometimes called...
= 2.07×10−15 V·s. The explanation provided by Little and Parks is that the resistance oscillation reflects a more fundamental phenomenon, i.e. periodic oscillation of the superconducting critical temperature (Tc). This is the temperature at which the sample becomes superconducting. The LP effect is a result of collective quantum behavior of superconducting electrons. It reflects the general fact that it is the fluxoid rather than the flux which is quantized in superconductors. The LP effect demonstrates that vector-potential couples to an observable physical quantity, namely the superconducting critical temperature.
Commercial activity
In 1962, the first commercial superconducting wire, a niobium-titaniumNiobium-titanium
Niobium-titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets...
alloy, was developed by researchers at Westinghouse.
In the same year, Josephson
Brian David Josephson
Brian David Josephson, FRS is a Welsh physicist. He became a Nobel Prize laureate in 1973 for the prediction of the eponymous Josephson effect....
made the important theoretical prediction that a supercurrent can flow between two pieces of superconductor separated by a thin layer of insulator. This phenomenon, now called the Josephson effect
Josephson effect
The Josephson effect is the phenomenon of supercurrent across two superconductors coupled by a weak link...
, is exploited by superconducting devices such as SQUID
SQUID
A SQUID is a very sensitive magnetometer used to measure extremely weak magnetic fields, based on superconducting loops containing Josephson junctions....
s. It is used in the most accurate available measurements of the magnetic flux quantum
Magnetic flux quantum
The magnetic flux quantum Φ0 is the quantum of magnetic flux passing through a superconductor. The phenomenon of flux quantization was discovered B. S. Deaver and W. M. Fairbank and, independently, by R. Doll and M. Nabauer, in 1961...
h/2e, and thus (coupled with the quantum Hall resistivity) for Planck's constant h. Josephson was awarded the Nobel Prize for this work in 1973.
In 1973 found to have Tc of 23 K which remained the highest ambient-pressure Tc until the discovery of the cuprate high temperature superconductors in 1986 (see below).
High temperature superconductors
In 1986, BednorzJohannes Georg Bednorz
Johannes Georg Bednorz is a physicist at the IBM Zürich Research Laboratory. He is best known for his role in the discovery of high-temperature superconductivity, for which he shared the 1987 Nobel Prize in Physics.-Life and work:...
and Mueller
Karl Alexander Müller
Karl Alexander Müller is a Swiss physicist and Nobel laureate. He received the Nobel Prize in Physics in 1987 with Johannes Georg Bednorz for their work in superconductivity in ceramic materials.-Biography:...
discovered superconductivity in a lanthanum
Lanthanum
Lanthanum is a chemical element with the symbol La and atomic number 57.Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table and is the first element of the lanthanide series. It is found in some rare-earth minerals, usually in combination with cerium and...
-based cuprate perovskite
Perovskite
A perovskite structure is any material with the same type of crystal structure as calcium titanium oxide , known as the perovskite structure, or XIIA2+VIB4+X2−3 with the oxygen in the face centers. Perovskites take their name from this compound, which was first discovered in the Ural mountains of...
material, which had a transition temperature of 35 K (Nobel Prize in Physics, 1987) and was the first of the high temperature superconductors. It was shortly found (by Ching-Wu Chu) that replacing the lanthanum with yttrium
Yttrium
Yttrium is a chemical element with symbol Y and atomic number 39. It is a silvery-metallic transition metal chemically similar to the lanthanides and it has often been classified as a "rare earth element". Yttrium is almost always found combined with the lanthanides in rare earth minerals and is...
, i.e. making YBCO, raised the critical temperature to 92 K, which was important because liquid nitrogen
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
could then be used as a refrigerant (at atmospheric pressure, the boiling point of nitrogen is 77 K.) This is important commercially because liquid nitrogen can be produced cheaply on-site with no raw materials, and is not prone to some of the problems (solid air plugs, etc.) of helium in piping. Many other cuprate superconductors have since been discovered, and the theory of superconductivity in these materials is one of the major outstanding challenges of theoretical condensed matter physics
Condensed matter physics
Condensed matter physics deals with the physical properties of condensed phases of matter. These properties appear when a number of atoms at the supramolecular and macromolecular scale interact strongly and adhere to each other or are otherwise highly concentrated in a system. The most familiar...
.
In March 2001 superconductivity of Magnesium diboride
Magnesium diboride
Magnesium diboride is a simple ionic binary compound that has proven to be an inexpensive and useful superconducting material.Its superconductivity was announced in the journal Nature in March 2001. Its critical temperature of is the highest amongst conventional superconductors...
was found with Tc of 39 K.
In 2008 the oxypnictide
Oxypnictide
In chemistry, oxypnictides are a class of materials including oxygen, a pnictogen and one or more other elements...
or iron-based superconductor
Iron-based superconductor
Iron-based superconductors are chemical compounds with superconducting properties. In 2008, led by recently discovered iron pnictide compounds , they were in the first stages of experimentation and implementation...
s were discovered which led to a flurry of work in the hope that studying them would provide a theory of the cuprate superconductors.
Historical publications
Onnes papers- "The resistance of pure mercury at helium temperatures" Comm. Leiden. April 28, 1911.
- "The disappearance of the resistivity of mercury". Comm. Leiden. May 27, 1911.
- "On the sudden change in the rate at which the resistance of mercury disappears". Comm. Leiden. November 25, 1911.
- "The imitation of an ampere molecular current or a permanent magnet by means of a supraconductor". Comm. Leiden.
BCS theory
- J. Bardeen, L.N. Cooper, and J.R. Schrieffer, Phys. Rev. 108, 1175 (1957)
Other papers
- W. Meissner and R. Ochsenfeld, Naturwiss. 21, 787 (1933)
- F. London and H. London, Proc. R. Soc. London A149, 71 (1935)
- V.L. Ginzburg and L.D. Landau, Zh. Eksp. Teor. Fiz. 20, 1064 (1950)
- E.Maxwell, Phys. Rev. 78, 477 (1950)
- C.A. Reynolds et al., Phys. Rev. 78, 487 (1950)
- W. A. Little and R. D. Parks, Physical Review Letters, Vol.9, page 9, (1962).
Other books
- M. Tinkham, “Introduction to Superconductivity”, 2nd Ed., McGraw-Hill, NY, 1996.
- Matricon, Jean; Waysand, Georges; Glashausser, Charles; The Cold Wars: A History of Superconductivity, Rutgers University Press, 2003, ISBN 0813532957 ... how the Cold WarCold WarThe Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
influenced the research in superconductivity
Patents
- Tesla, Nikola, "Means for Increasing the Intensity of Electrical Oscillations", March 21, 1900.
External links and references
- Onnes, Heike Kamerlingh, "Investigations into the properties of substances at low temperatures, which have led, amongst other things, to the preparation of liquid helium". Nobel Lecture, December 11, 1913.
- Shachtman, Tom, "Absolute Zero: And the Conquest of Cold". Houghton Mifflin Company, December 1999. ISBN 0-395-93888-0