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09 August 2023

Everything you needed to know about superconductors: A Q&A with Dr Mark Ainslie

The potential discovery of a new room-temperature superconductor (LK-99) has prompted many to dream of finally getting a hoverboard from Back To The Future. But what exactly is a superconductor? What’s so special about one being at room temperature, and what impact could it have on our daily lives?

Dr Mark Ainslie
Dr Mark Ainslie

We sat down with Dr Mark Ainslie, a Lecturer at the Department of Engineering and Superconductivity expert, to unpick the history of superconductors, their transformative impact on the world around us and when we might expect to be shredding it like Marty McFly.

What is a superconductor and when were they discovered?

Superconductors are materials, often metal compounds, that can conduct electricity with zero resistance and expel magnetic fields from within themselves – known as the Meissner effect. There are actually hundreds of materials that we’ve found to superconduct, but only around five that are used in practical applications today.

While most people think of superconductors as being incredibly futuristic, with future applications in everything from all-electric air transport to levitating trains, their origins stretch back to early 20th-century Europe.

Dr Mark Ainslie, Lecturer in Engineering

Superconductivity was discovered in 1911 by Kamerlingh Onnes at Leiden University in the Netherlands. He discovered that the electrical resistance of mercury abruptly dropped to zero around -269°C and this gave birth to the field of superconductivity. It was subsequently found that at low temperatures electrons flow in some materials along their length in a much more orderly fashion than how they usually do at higher temperatures. This means that less energy is lost from electrons crashing into each other and other atoms in the material, which explains why the electrical resistance dropped so remarkably.

Onnes immediately saw that this would revolutionise magnets, electrical power systems, motors, generators and more, making them more efficient, smaller and more powerful than ever before.

How are superconductors used today?

The reduced electrical resistance that superconductors offer in comparison to conventional copper wires means that devices using this technology can be made much more efficient, reducing energy waste. Superconducting materials can carry much higher currents through the same cross-section of wire than copper as well, leading to smaller, lighter and more powerful devices.

Superconductors allow us to make very powerful magnets, some of the strongest in the world. The biggest commercial application by far is magnetic resonance imaging or MRI. They are also used in particle accelerators for high-energy physics to understand the fundamental constituents of matter and ultimately understand the universe around us. They are essential for magnetic confinement fusion devices, which use magnetic fields to generate power by combining plasma together. These have long been seen as the clean and sustainable energy source needed to mitigate climate change and meet increasing energy demands.

There is ongoing research around the world to exploit superconductors’ remarkable material properties in almost all aspects of the electric power system, wind turbine generators, magnetic levitation (maglev) transport, superconducting electronics and quantum computing, new medical diagnostic and therapeutic technologies, and more – the list is long!

Scientists in South Korea say they have discovered a room-temperature superconductor, that they’ve called LK-99. How is LK-99 different from other superconductors and what's so special about one at room temperature?

Every superconductor that we know of today needs to be kept at sub-zero temperatures in order to operate. Even so called “high-temperature” superconductors need to be operated at around -200°C, roughly what we store liquid nitrogen at, or lower. Most practical superconducting applications actually still rely on technology first developed around the 1950s/60s.

This means that existing superconducting devices must have a cryogenic system accompanying it, which inevitably means that devices utilising this technology will inevitably be larger and more expensive. For engineers on the ground, this means weighing up the benefits and drawbacks of a massive increase in performance against the downsides of needing a cryogenic system.

The advantage of a room-temperature superconductor is that no cryogenic system would be needed for it to operate, which would mean that almost any device that uses electricity could be built better – more efficient, smaller, more powerful. It would likely result in the development of new technology that currently doesn’t exist.

Dr Mark Ainslie, Lecturer in Engineering

How transformational could a room temperature superconductor be, and is LK-99 likely to be it?

A room-temperature superconductor which works at the normal levels of atmospheric pressure found on Earth would be the “holy grail” of superconductivity research. If LK-99 is one such material, this would truly be a remarkable discovery. However, extraordinary claims require extraordinary proof, and dozens of researchers around the world are attempting to replicate the results right now.

The method of fabricating LK-99 has been detailed in the research papers put out by the team who claim to have discovered it and is not as complicated as some superconducting materials, meaning large amounts of specialist equipment are not required. However, this research has yet to be peer reviewed and attempts to replicate the experiment and synthesize LK-99 have so far failed. Therefore, the “holy grail” of superconductivity is unlikely to be here today, but a definitive picture of what LK-99 is, room temperature superconductor or not, should emerge soon.

How long could it take to truly develop a room-temperature superconductor and how would it impact everyday people?

Without the need for a cryogenic system, superconductors could be utilised in a range of devices and applications they haven’t been able to be used in yet. In our daily lives, you could imagine more efficient, smaller and more powerful superconducting computers, smartphones and electric vehicles, even superconducting wiring in your home. Essentially anything that uses electricity could be more efficient, waste less energy and be more compact.

Even if LK-99 is confirmed as a room temperature superconductor however, there’s still a long road ahead to it being deployed out in the real world. Superconductors need to be able to be made into long lengths of wire to be used in coil windings, which are wound stacks of electromagnetic wire used in magnets, motors, generators and transformers. They also need to be cheap enough to see widespread use in consumer products, and continue to carry large currents in the presence of the large magnetic fields, which something like a large motor would create.

The superconducting research community has been hard at work for decades improving our understanding of this revolutionary technology and how we might use it, but even if LK-99 were a room temperature superconductor, it could take a decade or more to refine into a practical form. However, we now live in a rapidly changing world where the pace of information dissemination and scientific developments have never been faster – so I’m keeping my fingers crossed for positive developments in this area (and possibly even cheap and affordable superconducting hoverboards for all!).

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Lecturer in Engineering