A superconductor is a type of material that, when cooled to a critical temperature, can conduct electricity with no resistance or energy loss. It achieves a state of “perfect conductivity,” or superconductivity, where an electric current can flow indefinitely.
Additionally, superconductors have the ability to suspend other objects in midair. Called diamagnetic levitation, these materials block out external magnetic forces by creating their own magnetic field, which repels a force stronger than gravity, in an event known as the Meissner effect.
Superconductor definition
A superconductor is a type of material that conducts electricity with zero energy loss or resistance when cooled to a certain temperature. No energy is lost, resulting in a continuously flowing electrical current.
Superconductivity cancels out electrical resistance and magnetic fields in a quantum mechanical phenomenon “that is fundamentally different from the way conventional conductors work,” Ryan Milton, director at MC Electrical & Communications, told Built In.
The main challenge is in its application. According to Milton, finding superconductive materials that activate at higher, “more practical” temperatures, then figuring out how they work, is “a frontier that scientists and engineers are actively exploring.”
This breakthrough seemed to emerge in July 2023, when a team of South Korean researchers claimed to have discovered the first “room-temperature, ambient-pressure” superconductor, with material they dubbed LK-99. Unfortunately, the claim is not supported by other scientists (the Condensed Matter Theory Center at the University of Maryland said that LK-99 is not a superconductor). Such a discovery would have been a game changer.
How Do Superconductors Work?
Regular conductors allow electricity to flow through them as a power source is applied. While this happens, something known as resistance occurs, which is when electrons climb from atom to atom, occasionally bumping into nuclei as they travel. This process expends energy and heats up a material. Once that power source is removed, the electrical current will cease.
This is not the case for superconductors, as their unique atomic makeup would maintain this electrical current.
A normal conductor becomes a superconductor when electrons are paired to “cooperate with a material’s vibrating atoms,” explained Michael McHenry, a professor of materials science and engineering at Carnegie Mellon University. These coupled electrons are known as Cooper pairs, and they spin in opposite directions as they move away from one another at the same speed. So instead of electrons taking any erratic path, they navigate the oscillating waves shared between electrons and the structure of a material, moving in sync with vibrating nuclei without friction. That allows them to avoid collisions, or scattering — the culprits of resistance.
The colder a material gets, the more organized these pathways become. Traditionally, that number nears absolute zero — the lowest possible limit on the thermodynamic scale, measuring at -459.67 degrees Fahrenheit, or 0 degrees Kelvin — however, it depends on the material.
New breakthroughs in recent years have discovered so-called high-temperature superconductors. These materials, typically ceramic copper-oxides, exhibit properties of superconductivity at relatively warm temperatures previously thought impossible. They can be chilled by liquid nitrogen, which keeps cool at 77 Kelvin, or -321.1 Fahrenheit.
“In a superconducting state, the electrons within the Cooper pairs … behave collectively as a single entity rather than individual particles,” said Shubham Munde, a senior research analyst for Market Research Future and whose focus includes semiconductors.
“By pushing the boundaries of temperature limitations, scientists are continuously striving to find materials that exhibit superconductivity at even higher temperatures,” Munde said. “The [aim is] to bring this transformative technology closer to room temperature, making it more feasible and cost-effective for widespread implementation in various industries.”
Superconductor Materials
Superconductors can be made out of metals, polymers or oxides.
This includes lead, tin or mercury to complex ceramic materials like rare-earth barium copper oxides. (Discovering the high-temperature superconductivity properties of ceramic won Georg Bednorz and Karl Müller the Nobel prize in 1987.)
Superconductor Examples and Applications
Medicine
In diagnostic care, superconducting magnets are the key component of MRI machines, which use superconductive wiring to create their own magnetic field, intensifying the penetrative power of the radio frequencies to gather optimal imaging. The medical field is also exploring their use in magnetic drug delivery systems and cancer cell detection.
“Their ability to generate high magnetic fields with low power consumption is critical,” Milton said.
Power Transmission
Superconducting cables can carry large currents with virtually no power loss, making this technology a sort of ‘holy grail’ for future power grids and electrical transmission networks.
Currently, variations of superconductive wiring — which transfers electricity at 200 times the copper standard — are being trialed and even government funded, according to the Department of Energy.
Scientific Research
Because of their unique properties, Milton said, superconductors are being used to break ground in a variety of scientific fields. Scientists are recruiting superconductors to explore physics as particle accelerators as well as nanowire detectors in the search for dark matter and subatomic particles known as neutrinos.
Quantum Computers
Superconductors hold promise to drive information processing to quantum speeds. Theoretically, these computers are powered by a circuit loop of electrical current, known as a superconducting qubit, maintained by superconductive materials.
“With the potential to form the basis of quantum computers,” Milton said, “[superconductors] would revolutionize information processing.”
Today’s most advanced quantum computer belongs to IBM’s The Osprey. It’s a 433-qubit quantum processor with a median coherence time around 70 to 80 microseconds that triples the size of its predecessor, The Eagle, according to Popular Science.
Maglev Trains
Maglev railways feature frictionless, all-electric trains that float above magnetic tracks at high speeds, upwards of 300 miles per hour. They run on two sets of superconducting systems, one to repel up and off the ground on a sort of air cushion and another to accelerate the train forward. They have been deemed “the most efficient form of ground transportation.” Today, there are only six operational maglev trains in existence.
Frequently Asked Questions
What was the first superconductor?
Mercury became the first known superconductor in 1911, when physicist Heike Kamerlingh Onnes and his team set the metal in temperatures below 4.2 Kelvin, or -452.11 Fahrenheit.
Examples of superconductors
Metals, ceramics and organic elements are materials capable of achieving superconductivity. Aluminium, magnesium diboride, niobium, iron pnictide as well as a mixture of yttrium, barium and copper oxides are common examples of superconductors.
What do we use superconductors for?
Superconducting electromagnets power MRI machines, maglev trains, nuclear fusion reactors and particle accelerators. In power transmission, superconductors can be used to enhance communication in power cables, fault current limiters, radio frequency and microwave filters. Other applications include quantum computers, engines, generators and magnetometers, which measure magnetic fields.