View source for Structural Basis of High-Temperature Superconductors

== Introduction ==

High-temperature superconductors (HTS) are materials that exhibit [[Superconductivity|superconducting]] properties at temperatures significantly higher than those of conventional superconductors. Unlike their low-temperature counterparts, which require cooling to near absolute zero to achieve superconductivity, HTS can operate at temperatures as high as 138 K (-135 °C). This makes them more practical for many applications, including power transmission, magnetic resonance imaging (MRI), and quantum computing.

[[Image:Detail-38427.jpg|thumb|center|A close-up view of a high-temperature superconductor material.|class=only_on_mobile]]
[[Image:Detail-38428.jpg|thumb|center|A close-up view of a high-temperature superconductor material.|class=only_on_desktop]]

== Discovery and Development ==

The first HTS was discovered in 1986 by [[J. Georg Bednorz|Bednorz]] and [[K. Alex Müller|Müller]], who were awarded the [[Nobel Prize in Physics]] for their groundbreaking work. Their discovery of superconductivity in a lanthanum-based ceramic material at a temperature of 35 K (-238 °C) was far above the previously known limit. This discovery ushered in a new era of superconductor research and development, leading to the discovery of many more HTS materials.

== Types of High-Temperature Superconductors ==

High-temperature superconductors are generally classified into two types: cuprate superconductors and iron-based superconductors.

=== Cuprate Superconductors ===

Cuprate superconductors are a family of HTS materials that contain layers of copper oxide. The first cuprate superconductor was the lanthanum-based ceramic material discovered by Bednorz and Müller. Since then, many other cuprate superconductors have been discovered, including yttrium barium copper oxide (YBCO), bismuth strontium calcium copper oxide (BSCCO), and thallium barium calcium copper oxide (TBCCO).

=== Iron-Based Superconductors ===

Iron-based superconductors, also known as iron pnictides, were discovered in 2008. These materials are structurally different from cuprates, as they contain layers of iron and a pnictogen (typically arsenic or phosphorus) instead of copper oxide. Despite their structural differences, iron-based superconductors exhibit similar superconducting properties to cuprates, including high critical temperatures and unconventional superconductivity.

== Mechanism of High-Temperature Superconductivity ==

The mechanism of high-temperature superconductivity is a topic of ongoing research. Unlike conventional superconductors, whose behavior can be explained by the [[BCS theory]], HTS do not fit into this framework. Several theories have been proposed to explain the behavior of HTS, including the resonating valence bond theory, the spin fluctuation theory, and the bipolaron theory. However, none of these theories have been universally accepted, and the mechanism of high-temperature superconductivity remains one of the unsolved problems in physics.

== Applications of High-Temperature Superconductors ==

High-temperature superconductors have a wide range of potential applications due to their ability to carry large amounts of current without resistance and generate strong magnetic fields. Some of the most promising applications for HTS include power transmission, magnetic resonance imaging (MRI), and quantum computing.

=== Power Transmission ===

HTS can be used to create power cables that are more efficient than traditional copper cables. Because they have no electrical resistance, HTS cables can carry large amounts of current without losing energy to heat. This makes them an attractive option for power transmission in urban areas, where space is limited and energy efficiency is a priority.

=== Magnetic Resonance Imaging ===

HTS materials can be used to create powerful magnets for MRI machines. Because they can generate strong magnetic fields at relatively high temperatures, HTS magnets are more practical and cost-effective than conventional superconducting magnets, which require cooling to near absolute zero.

=== Quantum Computing ===

HTS materials are also being explored for use in quantum computing. Because they exhibit macroscopic quantum phenomena, HTS could potentially be used to create qubits, the basic units of information in a quantum computer.

== Future Directions ==

While high-temperature superconductors hold great promise, there are still many challenges to overcome before they can be widely used. One of the main challenges is the need for high pressures to achieve superconductivity in these materials. Researchers are currently exploring ways to achieve superconductivity at ambient pressure, which would make HTS more practical for everyday use.

== See Also ==

* [[Superconductivity]]
* [[BCS theory]]
* [[Quantum computing]]
* [[Magnetic resonance imaging]]

[[Category:Superconductivity]]
[[Category:Materials science]]
[[Category:Condensed matter physics]]
[[Category:random]]