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Magnetism flips heat flow - Quantum effect points way to thermal electronics

Magnetism flips heat flow - Quantum effect points way to thermal electronics | superconductor | Scoop.it

The strange world of quantum mechanics just got a little stranger with the discovery that a magnetic field can control the flow of heat from from one body to another. First predicted nearly 50 years ago, the effect might some day form the basis of a new generation of electronic devices that use heat rather than charge as the information carrier.

 

The research stems from the work of physicist Brian Josephson, who in 1962 predicted that electrons could 'tunnel' between two superconductors separated by a thin layer of insulator — a process forbidden in classical physics. The Josephson junction was subsequently built and used to make superconducting quantum interference devices (SQUIDs), which are now sold commercially as ultra-sensitive magnetometers.


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Another step toward understanding of high-temperature superconductivity

Another step toward understanding of high-temperature superconductivity | superconductor | Scoop.it

Superconductors can revolutionize the way we use and distribute energy, change modes of transportation (e.g. Japan's magnetic levitation trains) and give us 100% energy-efficient technology. So why hasn't that happened yet? The problem is temperature! Most superconductors only work when they are cooled close to the forbidding absolute zero. The solution lies with those that work at higher temperatures.


Superconductors are materials that allow electrical current to flow with no energy loss, a phenomenon that can lead to a vastly energy-efficient future (imagine computers that never overheat). Although most superconductors work close to absolute zero (0°K or -273.15°C), some can operate at higher temperatures (around -135°C) – but how that happens is something of a mystery. Publishing in a recent PNAS article, Fabrizio Carbone's Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES) at EPFL has developed a method that can shed light on "high-temperature" superconductivity.

 

How conventional superconductivity works: When electricity passes through a conductor, e.g. a wire, some energy is lost because of resistance. This is not always a bad thing, since it can be used for heat (radiators) or light (light bulbs). But when it comes to things like national energy grids and high-voltage cables, electrical resistance (up to 7% in some grids) can mean money and constant wear. This is where superconductors come in. These are materials that, when cooled down enough, conduct electricity with no resistance – and therefore no loss. How? As superconductors cool below a certain temperature, their atoms fall in line and "nudge" charge-carrying electrons together to make new particles called Cooper pairs. These electron pairs observe quantum physics and form an unusual state of matter (a Bose-Einstein Condensate) that is not affected by electrical resistance.

Recently, the lab of Fabrizio Carbone at EPFL addressed the issue by developing a novel method that can advance our understanding of high-temperature superconductivity. High-temperature superconductors (HTS) show promise because they can operate at temperatures around -135°C – still low, but considerably cheaper and more feasible than for conventional superconductors. However, progress in HTS is limited because, even though we know that Cooper pairs are involved in high-temperature superconductivity, there is no consensus as to how they are formed. Carbone's group was able, for the first time, to directly observe the formation of Cooper pairs in real time in a superconducting HTS and determine how the process affects the optical properties of the superconductor. Using a novel approach, the scientists cooled an HTS to its superconducting temperature and then repeatedly fired laser pulses on it to break up the Cooper pairs back into single electrons. As the Cooper pairs broke and re-formed, they caused a periodical change in the color spectrum of the superconductor. By measuring the color change, the researchers were able to directly study what happens in a superconducting HTS. What they discovered was that Cooper pair formation follows a completely different path than in conventional superconductors. Carbone's findings mark the first direct observation of Cooper pair formation in HTS superconductivity. They also provide scientists with a powerful tool to observe the phenomenon in real time. The hope is that by extending this innovative approach to different materials, we can begin to understand how high-temperature superconductivity really works.


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Victoria Hull's curator insight, October 26, 2014 12:46 PM

This article starts off by explaining that the downside of superconductors is that they require very low temperatures to work (absolute zero). It then explains that superconductors work because when the temperature is low the atom line up and nudge electrons together forming cooper pairs. These pairs allow a different path to be used than the path in a standard conductor.

Group 8's curator insight, October 26, 2014 6:10 PM

This papers shows how we understand the processes that occur in superconducting materials to give them the properties that are desired. Superconductors are split into two kinds conventional that only work at tempertaures approaching absolute zero and HTS ( High Temperature superconductors). The HTS superconductoirs are of more interest as for practical use being a superconducting material at 0K has no practical uses. this study shows that in a superconductor electrons become pairs called cooper pairs and become a new state of matter known as Bose-Einstein condensates which are completely unaffected by resistance and the formation of this matter is of interest. this study observed the formation by using laser beams to break the pairs and watch them reform in real time, therefore observing the pathway in which thy form. 

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String Theory Helps To Explain Quantum Phases Of Matter

String Theory Helps To Explain Quantum Phases Of Matter | superconductor | Scoop.it

Newly discovered states of matter embody what Einstein called “spooky action at a distance.” They defy explanation, but lately answers have come from a seemingly unrelated corner of physics: string theory.

 

Matter can assume many forms other than solid, liquid and gas. The electrons that perfuse materials can undergo their own transitions, which involve inherently quantum properties of matter. Superconductors are the best-known example.These states of matter arise from an unimaginably complex web of quantum entanglement among the electrons—so complex that theorists studying these materials have been at a loss to describe them.

 

Some answers have come from an entirely separate line of study, string theory, typically the domain of cosmologists and high-energy particle theorists. On the face of it, string theory has nothing to say about the behavior of materials—no more than an atomic physicist can explain human society. And yet connections exist.


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Desarrollan un método que mejora la superconductividad / Noticias / SINC / Servicio de Información y Noticias Científicas

Desarrollan un método que mejora la superconductividad / Noticias / SINC / Servicio de Información y Noticias Científicas | superconductor | Scoop.it
SINC, Servicio de Información y Noticias Científicas, plataforma multimedia de comunicación científica
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Aplicacion de los superconductores

Aplicacion de los superconductores | superconductor | Scoop.it
Aplicaciones de los superconductores. Las aplicaciones de los materiales superconductivos están limitadas por dos motivos principales: 1.- La necesidad de
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NIST's prototype solid-state refrigerator uses quantum physics for extreme cooling to less than 1 Kelvin

NIST's prototype solid-state refrigerator uses quantum physics for extreme cooling to less than 1 Kelvin | superconductor | Scoop.it

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a solid-state refrigerator that uses quantum physics in micro- and nanostructures to cool a much larger object to extremely low temperatures.

 

What's more, the prototype NIST refrigerator, which measures a few inches in outer dimensions, enables researchers to place any suitable object in the cooling zone and later remove and replace it, similar to an all-purpose kitchen refrigerator. The cooling power is the equivalent of a window-mounted air conditioner cooling a building the size of the Lincoln Memorial in Washington, D.C.

 

"It's one of the most flabbergasting results I've seen," project leader Joel Ullom says. "We used quantum mechanics in a nanostructure to cool a block of copper. The copper is about a million times heavier than the refrigerating elements. This is a rare example of a nano- or microelectromechanical machine that can manipulate the macroscopic world."

 

The technology may offer a compact, convenient means of chilling advanced sensors below standard cryogenic temperatures—300 milliKelvin (mK), typically achieved by use of liquid helium—to enhance their performance in quantum information systems, telescope cameras, and searches for mysterious dark matter and dark energy.

 

The NIST refrigerator's cooling elements, consisting of 48 tiny sandwiches of specific materials, chilled a plate of copper, 2.5 centimeters on a side and 3 millimeters thick, from 290 mK to 256 mK. The cooling process took about 18 hours. NIST researchers expect that minor improvements will enable faster and further cooling to about 100 mK.

 

The cooling elements are sandwiches of a normal metal, a 1-nanometer-thick insulating layer, and a superconducting metal. When a voltage is applied, the hottest electrons "tunnel" from the normal metal through the insulator to the superconductor. The temperature in the normal metal drops dramatically and drains electronic and vibrational energy from the object being cooled.

 

NIST researchers previously demonstrated this basic cooling method** but are now able to cool larger objects that can be easily attached and removed. Researchers developed a micromachining process to attach the cooling elements to the copper plate, which is designed to be a stage on which other objects can be attached and cooled. Additional advances include better thermal isolation of the stage, which is suspended by strong, cold-tolerant cords.

 

Cooling to temperatures below 300 mK currently requires complex, large and costly apparatus. NIST researchers want to build simple, compact alternatives to make it easier to cool NIST's advanced sensors. Researchers plan to boost the cooling power of the prototype refrigerator by adding more and higher-efficiency superconducting junctions and building a more rigid support structure.

 


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A new look at high-temperature superconductors

A new look at high-temperature superconductors | superconductor | Scoop.it

MIT researchers' new method for observing the motion of electron density waves in a superconducting material led to the detection of two different kinds of variations in those waves: amplitude (or intensity) changes and phase changes, shifting the relative positions of peaks and troughs of intensity. These new findings could make it easier to search for new kinds of higher-temperature superconductors.

 

 While the phenomenon of superconductivity — in which some materials lose all resistance to electric currents at extremely low temperatures — has been known for more than a century, the temperature at which it occurs has remained too low for any practical applications. The discovery of “high-temperature” superconductors in the 1980s — materials that could lose resistance at temperatures of up to negative 140 degrees Celsius — led to speculation that a surge of new discoveries might quickly lead to room-temperature superconductors. Despite intense research, these materials have remained poorly understood.


There is still no agreement on a single theory to account for high-temperature superconductivity. Recently, however, researchers at MIT and elsewhere have found a new way to study fluctuating charge-density waves, which are the basis for one of the leading theories. The researchers say this could open the door to a better understanding of high-temperature superconductivity, and perhaps prompt new discoveries of higher-temperature superconductors.


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Mercor's curator insight, February 25, 2013 11:59 AM

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Group7's curator insight, October 20, 2014 7:56 AM

This shows MIT researchers' new method for observing the motion of electron density waves in a superconducting material which led to the detection of two different kinds of variations in those waves: amplitude changes and phase changes, shifting the relative positions of peaks and troughs of intensity. These new findings could make it easier to search for new kinds of higher-temperature superconductors.

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Dispositivos superconductores de interferencia cuántica, ¿hacia un horizonte de eventos artificial? — Noticias de la Ciencia y la Tecnología (Amazings® / NCYT®)

Dispositivos superconductores de interferencia cuántica, ¿hacia un horizonte de eventos artificial? — Noticias de la Ciencia y la Tecnología (Amazings®  / NCYT®) | superconductor | Scoop.it
Noticias científicas y tecnológicas, artículos y entrevistas sobre el mundo de la ciencia
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Clasificación de los superconductores - Wikipedia, la enciclopedia libre

Los superconductores se suelen clasificar atendiendo a distintos criterios, que pueden estar relacionados con su comportamiento físico, la comprensión que tenemos de ellos, dependiendo del coste económico para utilizarlos o el material de que están hechos.

Este criterio se debe al físico Alekséi Abrikósov y fue propuesto en 1957.[1][2] De forma más rigurosa se emplea el parámetro de Ginzburg-Landau, de modo que

La importancia de este criterio de clasificación se basa en que tenemos una teoría, la teoría BCS, que explica con éxito las propiedades de los superconductores convencionales desde 1957, mientras que no hay aún una teoría satisfactoria para los superconductores no convencionales. Para estudiar los superconductores no convencionales se suele emplear la teoría Ginzburg-Landau, que sin embargo es una teoría macroscópica (es decir, no explica las propiedades a partir de primeros principios como sí hace la teoría BCS, que es una teoría microscópica). El estudio riguroso de los superconductores no convencionales es un problema no resuelto en física.

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Pushing the bounds of superconductivity: New unique multilayer materia designed to be extraordinary superconducting

Pushing the bounds of superconductivity: New unique multilayer materia designed to be extraordinary superconducting | superconductor | Scoop.it

A multi-university team of researchers has artificially engineered a unique multilayer material that could lead to breakthroughs in both superconductivity research and in real-world applications. 

 

The researchers can tailor the material, which seamlessly alternates between metal and oxide layers, to achieve extraordinary superconducting properties - in particular, the ability to transport much more electrical current than non-engineered materials. 

 

The team includes experts from the University of Wisconsin-Madison, Florida State University and the University of Michigan. Led by Chang-Beom Eom, the Harvey D. Spangler Distinguished Professor of materials science and engineering and physics at UW-Madison, the group described its breakthrough March 3, 2013, in the advance online edition of the journal Nature Materials. 

 

Superconductors, which presently operate only under extremely cold conditions, transport energy very efficiently. With the ability to transport large electrical currents and produce high magnetic fields, they power such existing technologies as magnetic resonance imaging and Maglev trains, among others. They hold great potential for emerging applications in electronic devices, transportation, and power transmission, generation and storage. 

 

Carefully layered superconducting materials are increasingly important in highly sophisticated applications. For example, a superconducting quantum interference device, or SQUID, used to measure subtle magnetic fields in magnetoencephalography scans of the brain, is based on a three-layer material. 

 

However, one challenge in the quest to understand and leverage superconductivity is developing materials that work at room temperature. Currently, even unconventional high-temperature superconductors operate below -369 degrees Fahrenheit.

 

An unconventional high-temperature superconductor, the researchers' iron-based "pnictide" material is promising in part because its effective operating temperature is higher than that of conventional superconducting materials such as niobium, lead or mercury. 

 

The research team engineered and measured the properties of superlattices of pnictide superconductors. A superlattice is the complex, regularly repeating geometric arrangement of atoms—its crystal structure—in layers of two or more materials. Pnictide superconductors include compounds made from any of five elements in the nitrogen family of the periodic table. 

 

The researchers' new material is composed of 24 layers that alternate between the pnictide superconductor and a layer of the oxide strontium titanate. Creating such systems is difficult, especially when the arrangement of atoms, and chemical compatibility, of each material is very different. 

Yet, layer after layer, the researchers maintained an atomically sharp interface—the region where materials meet. Each atom in each layer is precisely placed, spaced and arranged in a regularly repeating crystal structure. 

The new material also has improved current-carrying capabilities. As they grew the superlattice, the researchers also added a tiny bit of oxygen to intentionally insert defects every few nanometers in the material. These defects act as pinning centers to immobilize tiny magnetic vortices that, as they grow in strength in large magnetic fields, can limit current flow through the superconductor. "If the vortices move around freely, the energy dissipates, and the superconductor is no longer lossless," says Eom. "We have engineered both vertical and planar pinning centers, because vortices created by magnetic fields can be in many different orientations."

 

Eom sees possibilities for researchers to expand upon his team's success in engineering man-made superconducting structures. "There's a need to engineer superlattices for understanding fundamental superconductivity, for potential use in high-field and electronic devices, and to achieve extraordinary properties in the system," says Eom. "And, there is indication that interfaces can be a new area of discovery in high-temperature superconductors. This material offers those possibilities."


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group12a's curator insight, October 26, 2014 7:54 PM

In this article, a multilayer material was designed to improve the transport of electrical current. They work really effectively under -369 Kelvin to produce magnetic fields, which are useful to resonance magnetic imaging machines and Maglev trains. The challenge is to make these improvements under high temperatures.  The "iron based penictid"  is an unusual superconductor because can work under this condition. The benefits of this kind of superconductor would be the clear improvement for electronic devices use.  

Group7's curator insight, October 27, 2014 6:18 AM

This is an article explaining a new superconducting material made from pnictide superconductor and strontium titanate and how it is showing to be a high temperature superconductor. Developments of high temperature superconductors are needed at the moment and this article shows the possibilities in new superconducting materials at higher temperatures with higher current carrying abilities due to structure.