Type-II superconductor
Encyclopedia
A Type-II superconductor is a superconductor characterized by the formation of vortex lattices in magnetic field. It has a continuous second order phase transition from the superconducting to the normal state within an increasing magnetic field.
The possibility of type-II superconductivity was theoretically predicted by Alexei Alexeyevich Abrikosov
, for which a Nobel Prize in Physics
was awarded in 2003.
s, whereas most superconducting pure metals are Type-I superconductors.
All high temperature superconductors are Type-II superconductors, and (as of early 2008) comprise mostly complex copper oxide ceramics. While most pure metal or pure element superconductors are Type-I, niobium
, vanadium
, and technetium
are pure element Type-II superconductors. Boron
-doped diamond
and silicon
are also Type-II superconductors. Metal alloy superconductors also exhibit Type-II behavior (e.g. niobium-titanium
, niobium-tin
).
Niobium-tin
was discovered in 1954.
Other Type-II examples are the cuprate
-perovskite
ceramic materials which have achieved the highest temperatures to reach the superconducting state. These include La1.85Ba0.15CuO4, BSCCO, and YBCO (Yttrium
-Barium
-Copper
-Oxide
), which is famous as the first material to achieve superconductivity above the boiling point of liquid nitrogen. However, the lattice of graphene that was experimented with is also believed to be a Type-II superconductor.
In 2001 Magnesium diboride
was discovered to be a type-II SC with useful properties. Until the discovery of the iron-arsenide family
, It was the highest temperature superconductor not containing copper.
machines, and particle accelerator
s) often use niobium-titanium
or, for higher fields, niobium-tin
.
).
of a superconductor, related to the mean free path of its charge carriers, and a penetration depth.
The earlier London penetration depth
is the penetration distance of a weak magnetic field.
In a Type-II superconductor, the coherence length is smaller than the London penetration depth. This is known as the vortex state, as the flux lines run through narrow regions of non superconducting material, surrounded by vortices of supercurrents protecting the rest of the superconductor. The vortices can arrange themselves in a regular structure known as the vortex lattice, also named the Abrikosov vortex
, after Alexei Alexeyevich Abrikosov
, who was awarded the 2003 Nobel Prize in Physics
for his pioneering contributions.
The possibility of type-II superconductivity was theoretically predicted by Alexei Alexeyevich Abrikosov
Alexei Alexeyevich Abrikosov
Alexei Alexeyevich Abrikosov is a Soviet and Russian theoretical physicist whose main contributions are in the field of condensed matter physics. He was awarded the Nobel Prize in Physics in 2003.- Biography :...
, for which a 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...
was awarded in 2003.
Materials
Type-II superconductors are usually made of metal alloys or complex oxide ceramicCeramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
s, whereas most superconducting pure metals are Type-I superconductors.
All high temperature superconductors are Type-II superconductors, and (as of early 2008) comprise mostly complex copper oxide ceramics. While most pure metal or pure element superconductors are Type-I, niobium
Niobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
, vanadium
Vanadium
Vanadium is a chemical element with the symbol V and atomic number 23. It is a hard, silvery gray, ductile and malleable transition metal. The formation of an oxide layer stabilizes the metal against oxidation. The element is found only in chemically combined form in nature...
, and technetium
Technetium
Technetium is the chemical element with atomic number 43 and symbol Tc. It is the lowest atomic number element without any stable isotopes; every form of it is radioactive. Nearly all technetium is produced synthetically and only minute amounts are found in nature...
are pure element Type-II superconductors. Boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
-doped diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
and silicon
Silicon
Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table...
are also Type-II superconductors. Metal alloy superconductors also exhibit Type-II behavior (e.g. niobium-titanium
Niobium-titanium
Niobium-titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets...
, niobium-tin
Niobium-tin
Niobium-tin or triniobium-tin is a metallic chemical compound of niobium and tin , used industrially as a type II superconductor. This intermetallic compoundis a A15 phases superconductor...
).
Niobium-tin
Niobium-tin
Niobium-tin or triniobium-tin is a metallic chemical compound of niobium and tin , used industrially as a type II superconductor. This intermetallic compoundis a A15 phases superconductor...
was discovered in 1954.
Other Type-II examples are the cuprate
Cuprate
Cuprates are chemical compounds containing copper anion. Cuprates have been known for centuries and are widely used in inorganic and organic chemistry...
-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...
ceramic materials which have achieved the highest temperatures to reach the superconducting state. These include La1.85Ba0.15CuO4, BSCCO, and YBCO (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...
-Barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
-Copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
-Oxide
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
), which is famous as the first material to achieve superconductivity above the boiling point of liquid nitrogen. However, the lattice of graphene that was experimented with is also believed to be a Type-II superconductor.
In 2001 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 discovered to be a type-II SC with useful properties. Until the discovery of the iron-arsenide family
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...
, It was the highest temperature superconductor not containing copper.
Important uses
Strong superconducting electromagnets (used in MRI scanners, NMRNMR
NMR may refer to:Applications of Nuclear Magnetic Resonance:* Nuclear magnetic resonance* NMR spectroscopy* Solid-state nuclear magnetic resonance* Protein nuclear magnetic resonance spectroscopy* Proton NMR* Carbon-13 NMR...
machines, and particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
s) often use niobium-titanium
Niobium-titanium
Niobium-titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets...
or, for higher fields, niobium-tin
Niobium-tin
Niobium-tin or triniobium-tin is a metallic chemical compound of niobium and tin , used industrially as a type II superconductor. This intermetallic compoundis a A15 phases superconductor...
.
Critical fields
The continuous transition to a vortex state (flux penetration) occurs at first critical magnetic field Hc1 and system loses superconductivity at second critical magnetic field Hc2 (the upper critical fieldUpper critical field
-Upper critical field:The upper critical field is the magnetic field which completely suppresses superconductivity in a Type II superconductor at 0K ....
).
Vortex state
Ginzburg–Landau theory defines 2 parameters: The coherence lengthCoherence length
In physics, coherence length is the propagation distance from a coherent source to a point where an electromagnetic wave maintains a specified degree of coherence. The significance is that interference will be strong within a coherence length of the source, but not beyond it...
of a superconductor, related to the mean free path of its charge carriers, and a penetration depth.
The earlier London penetration depth
London penetration depth
In superconductors, the London penetration depth characterizes the distance to which a magnetic field penetrates into a superconductor and becomes equal to 1/e times that of the magnetic field at the surface of the superconductor...
is the penetration distance of a weak magnetic field.
In a Type-II superconductor, the coherence length is smaller than the London penetration depth. This is known as the vortex state, as the flux lines run through narrow regions of non superconducting material, surrounded by vortices of supercurrents protecting the rest of the superconductor. The vortices can arrange themselves in a regular structure known as the vortex lattice, also named the Abrikosov vortex
Abrikosov vortex
In superconductivity, an Abrikosov vortex is a vortex of supercurrent in a type-II superconductor. The supercurrent circulates around the normal core of the vortex. The core has a size \sim\xi — the superconducting coherence length...
, after Alexei Alexeyevich Abrikosov
Alexei Alexeyevich Abrikosov
Alexei Alexeyevich Abrikosov is a Soviet and Russian theoretical physicist whose main contributions are in the field of condensed matter physics. He was awarded the Nobel Prize in Physics in 2003.- Biography :...
, who was awarded the 2003 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...
for his pioneering contributions.
See also
- Conventional superconductorConventional superconductorConventional superconductors are materials that display superconductivity as described by BCS theory or its extensions.Critical temperatures of some simple metals:ElementTc Al1.20Hg4.15Mo0.92Nb9.26Pb7.19...
- Covalent superconductorsCovalent superconductorsCovalent semiconductors are such solids as diamond, silicon, germanium, silicon carbide and silicon-germanium where atoms are linked by covalent bonds. Most of those materials, at least in their bulk form, are well studied and rarely hit the front pages of the top scientific journals in the last...
- Flux pumpingFlux pumpingFlux pumping is a method for magnetising bulk superconductors to fields in excess of 15 teslas. The method can be applied to any type II superconductor and exploits a fundamental property of superconductors. That is their ability to support and maintain currents on the length scale of the...
- List of superconductors
- High-temperature superconductivityHigh-temperature superconductivityHigh-temperature superconductors are materials that have a superconducting transition temperature above . From 1960 to 1980, 30 K was thought to be the highest theoretically possible Tc...
- Room temperature superconductorRoom temperature superconductorA room-temperature superconductor is a material yet to be discovered which would be capable of exhibiting superconducting properties at operating temperatures above 0° C . This is not strictly speaking "room temperature" A room-temperature superconductor is a material yet to be discovered...
- SuperconductivitySuperconductivitySuperconductivity 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...
- Superconductor classificationSuperconductor classificationSuperconductors can be classified in accordance with several criteria that depend on our interest in their physical properties, on the understanding we have about them, on how expensive is cooling them or on the material they are made of....
- Technological applications of superconductivityTechnological applications of superconductivitySome of the technological applications of superconductivity include:* the production of sensitive magnetometers based on SQUIDs* fast digital circuits ,...
- Timeline of low-temperature technologyTimeline of low-temperature technologyThe following is a timeline of low-temperature technology and cryogenic technology .-16th century BCE – 17th century CE :...
- Type-I superconductor
- Type-1.5 superconductor
- Unconventional superconductorUnconventional superconductorUnconventional superconductors are materials that display superconductivity which does not conform to either the conventional BCS theory or the Nikolay Bogolyubov's theory or its extensions....
- Bean's critical state modelBean's critical state modelBean's critical state model, introduced by C. P. Bean in 1962, gives a macroscopic explanation of the irreversible magnetization behavior of hard Type-II superconductors.-Assumptions:...