Superstripes
Encyclopedia
Superstripes are metallic heterostructures at the atomic limit where the shape resonance
in the energy gap parameters ∆n is the driving mechanism for the amplification of the superconductivity
critical temperature. These particular heterostructures at atomic limit are formed by a metallic superlattice
of superconducting units (layers, or stripes, or wires, or spheres or balls) separated by an intercalated
material as in cuprate
materials.
The superstripes show multiple superconducting gaps, i.e. different order parameters of the off diagonal superconducting order, therefore these materials are a particular case of the called two-band superconductor or multiband superconductor or two-gap superconductor, or multigap superconductor. A key particular feature of superstripes is that the different gaps are not only different in different portions of the k-space but also in different portions of the superlattice in the real space.
: the structural modulation that coexists and favors high temperature superconductivity
belonging to the group of Fano Feshbach resonances in atomic and nuclear physics. The quantum resonance is switched on when the chemical potential is tuned at an "electronic topological transition" (ETT) where one of the Fermi surfaces of the subbands appears or changes its dimensionality. The tuning of the chemical potential at the shape resonance
can be obtained by changing: the charge density and/or the superlattice structural parameters, and/or the superlattice misfit strain and/or the disorder.
made of superstripes are the cuprate
materials made of cupric oxide layers intercalated by block layers, the magnesium diboride
materials made of boron
layers intercalated by Magnesium
/Aluminium
/Scandium
layers and the oxypnictide
materials made of iron
arsenide
layers intercalated by atomic or oxide layers.
Shape resonance
A shape resonance is a metastable state in which an electron is trapped due the shape of a potential barrier.Serhan describes a state as being a shape resonance if, "the internal state of the system remains unchanged upon disintegration of the quasi-bound level."A more general discussion of...
in the energy gap parameters ∆n is the driving mechanism for the amplification of the 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...
critical temperature. These particular heterostructures at atomic limit are formed by a metallic superlattice
Superlattice
Superlattice is a periodic structure of layers of two materials. Typically, the thickness of one layer is several nanometers.- Discovery :Superlattices were discovered early in the 20th century through their special X-ray diffraction patterns....
of superconducting units (layers, or stripes, or wires, or spheres or balls) separated by an intercalated
Intercalation (chemistry)
In chemistry, intercalation is the reversible inclusion of a molecule between two other molecules . Examples include DNA intercalation and graphite intercalation compounds.- DNA intercalation :...
material as in cuprate
Cuprate
Cuprates are chemical compounds containing copper anion. Cuprates have been known for centuries and are widely used in inorganic and organic chemistry...
materials.
The superstripes show multiple superconducting gaps, i.e. different order parameters of the off diagonal superconducting order, therefore these materials are a particular case of the called two-band superconductor or multiband superconductor or two-gap superconductor, or multigap superconductor. A key particular feature of superstripes is that the different gaps are not only different in different portions of the k-space but also in different portions of the superlattice in the real space.
History
The name Superstripes was introduced in 1999 for describing the intrinsic structural feature of materials showing High-temperature superconductivityHigh-temperature superconductivity
High-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...
: the structural modulation that coexists and favors high temperature superconductivity
High temperature superconductivity in superstripes
The prediction of high temperature superconductivity transition temperatures is rightly considered to be one of the most difficult problems in theoretical physics. The High Temperature Superconductivity in Superstripes is driven by a quantum mechanism that rises the critical temperature: a quantum interference effect in the Interband Pairing, that is a resonance in the exchange-like pair transfer between different condensates, providing a single critical temperature Tc. The quantum configuration interaction between different pairing channels is a particular case of shape resonanceShape resonance
A shape resonance is a metastable state in which an electron is trapped due the shape of a potential barrier.Serhan describes a state as being a shape resonance if, "the internal state of the system remains unchanged upon disintegration of the quasi-bound level."A more general discussion of...
belonging to the group of Fano Feshbach resonances in atomic and nuclear physics. The quantum resonance is switched on when the chemical potential is tuned at an "electronic topological transition" (ETT) where one of the Fermi surfaces of the subbands appears or changes its dimensionality. The tuning of the chemical potential at the shape resonance
Shape resonance
A shape resonance is a metastable state in which an electron is trapped due the shape of a potential barrier.Serhan describes a state as being a shape resonance if, "the internal state of the system remains unchanged upon disintegration of the quasi-bound level."A more general discussion of...
can be obtained by changing: the charge density and/or the superlattice structural parameters, and/or the superlattice misfit strain and/or the disorder.
Materials
The particular realizations of this type of unconventional superconductorUnconventional superconductor
Unconventional 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....
made of superstripes 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...
materials made of cupric oxide layers intercalated by block layers, the 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...
materials made of 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...
layers intercalated by Magnesium
Magnesium
Magnesium is a chemical element with the symbol Mg, atomic number 12, and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the Earth's crust and ninth in the known universe as a whole...
/Aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
/Scandium
Scandium
Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids...
layers and the oxypnictide
Oxypnictide
In chemistry, oxypnictides are a class of materials including oxygen, a pnictogen and one or more other elements...
materials made of iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
arsenide
Arsenide
Arsenide is an arsenic anion with the charge −3. The trianion is formed by the reduction of arsenic by three electrons. For example heating arsenic powder with excess sodium gives sodium arsenide . The anions have no existence in solution since they are extremely basic...
layers intercalated by atomic or oxide layers.
Superstripes conferences
Superstripes has given the name to a series of conferences dedicated on this subject that started in 2008, "Superstripes 2008". The second "Superstripes 2010" meeting will be held in Erice, Italy July 19–25 (2010)External links
- Superstripes 2008 http://www.roma1.infn.it/stripes/Menu/006Conferences/SuperStripes08/SuperStr08home.html
- Superstripes 2010 http://www.roma1.infn.it/stripes/Menu/006Conferences/SuperStripes10/Str10home.html
- Superstripes web page http://www.roma1.infn.it/stripes/index.html