̽��ֱ�� of Cambridge - Suchitra E. Sebastian

Professor Suchitra Sebastian to receive the Schmidt Science Polymaths Award

sc604 — Thu, 30 Jun 2022 11:30:16 +0000

Professor Suchitra Sebastian from Cambridge’s Cavendish Laboratory has been awarded the Schmidt Science Polymaths award. Schmidt Futures, a philanthropic initiative founded by Eric and Wendy Schmidt, announced ten new recipients of the award, which provides $500,000 a year, paid through their institution, for up to five years to help support part of a research group.

̽��ֱ��Polymath programme makes long-term bets on recently-tenured professors with remarkable track records, promising futures, and a desire to explore risky new research ideas across disciplines. ̽��ֱ��awardees are the second group to receive the Polymath award, joining just two other exceptionally talented interdisciplinary researchers named in 2021. ̽��ֱ��awards build upon Schmidt Futures’ commitment to identifying and supporting extraordinary talent, and growing networks empowered to solve hard problems in science and society.

Professor Sebastian’s research seeks to discover exotic quantum phases of matter in complex materials. Her group’s experiments involve tuning the co-operative behaviour of electrons within these materials by subjecting them to extreme conditions including low temperature, high applied pressure, and intense magnetic field.

Under these conditions, her group can take materials that are quite close to behaving like a superconductor – perfect, lossless conductors of electricity – and ‘nudge’ them, transforming their behaviour.

“I like to call it quantum alchemy – like turning soot into gold,” Sebastian said. “You can start with a material that doesn’t even conduct electricity, squeeze it under pressure, and discover that it transforms into a superconductor. Going forward, we may also discover new quantum phases of matter that we haven’t even imagined.”

Other awards she has received for her research include the World Economic Forum Young Scientist award, the L'Oreal-UNESCO Fellowship, the Lee Osheroff Richardson North American Science prize, the International Young Scientist Medal in Magnetism, the Moseley Medal, the Philip Leverhulme Prize, the Brian Pippard Prize. She is an ERC starting and consolidator grant awardee. Most recently, she was awarded the New Horizons in Physics Prize (2022) by the Breakthrough Foundation.

In addition to her physics research, Sebastian is also involved in theatre and the arts. She is Director of the Cavendish Arts-Science Project, which she founded in 2016. ̽��ֱ��programme has been conceived to question and explore material and immaterial universes through a dialogue between the arts and sciences.

“ ̽��ֱ��very idea of the Polymath Award is revolutionary,” said Sebastian. “It's so rare that an award selects people for being polymaths. Imagining new worlds and questioning traditional ways of knowing - whether by doing experimental theatre, or by bringing together art and science, is part of who I am.

“And this is why in our group, we love to research at the edge - to make risky boundary crossings and go on wild adventures into the quantum unknown. We do it because it's incredibly fun, you never know what each day will bring. To be recognised for this by Schmidt Futures is so unexpected and exciting, the possibilities this award opens up are endless. I look forward to embarking on new quantum explorations, it’s going to be a wild ride!”

̽��ֱ��awards build upon Schmidt Futures’ commitment to identifying and supporting extraordinary talent, and growing networks empowered to solve hard problems in science and society. Each Polymath will receive support at the moment in their careers when researchers have the most freedom to explore new ideas, use emerging technologies to test risky theories, and pursue novel scientific research that traverses fields and disciplines; which is otherwise unlikely to receive funding or support.

“ ̽��ֱ��interdisciplinary work that could herald the next great scientific breakthroughs are chronically under-funded,” said Eric Braverman, CEO of Schmidt Futures. “We are betting on the talent of the Schmidt Science Polymaths to explore new ideas across disciplines and accelerate discoveries to address the challenges facing our planet and society.”

Hopeful Polymaths from over 25 universities submitted applications outlining research ideas in STEM fields that represent a substantive shift from their current research portfolio and are unlikely to receive funding elsewhere for consideration to the Schmidt Science Polymaths program. Existing Polymaths’ ideas range from the artificial creation of complex soft matter like human tissue, to the development of synthetic biology platforms for engineering multicellular systems, to the discovery of exotic forms of quantum matter. ̽��ֱ��impact of this type of interdisciplinary research could result in innovations previously thought impossible like a 3D printer for human organs, climate change-resistant crops, or the unknown applications of quantum matter.

“Single-minded -specialisation coupled with rigid research and funding structures often hinder the ambition to unleash fresh perspectives in scientific inquiry,” said Stuart Feldman, Chief Scientist of Schmidt Futures. “From climate change to public health, the Schmidt Science Polymaths utilise the depth of their knowledge across a breadth of fields to find new ways to solve some of our hardest problems for public benefit.”

Cambridge physicist Professor Suchitra Sebastian to join group of ten recently tenured professors named to Polymath Program, awarded up to $2.5 million each for interdisciplinary research support.

To be recognised for this by Schmidt Futures is so unexpected and exciting, the possibilities this award opens up are endless. I look forward to embarking on new quantum explorations, it’s going to be a wild ride!

Suchitra Sebastian

Nick Saffell

Suchitra Sebastian

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Four Cambridge researchers recognised in the 2022 Breakthrough Prizes

sc604 — Thu, 09 Sep 2021 11:59:47 +0000

Professors Shankar Balasubramanian and David Klenerman, from Cambridge’s Yusuf Hamied Department of Chemistry, have been awarded the 2022 Breakthrough Prize in Life Sciences – the world’s largest science prize – for the development of next-generation DNA sequencing. They share the award with Pascal Mayer, from the French company Alphanosos.

In addition, Professor Suchitra Sebastian, from the Cavendish Laboratory, and Professor Jack Thorne, from the Department of Pure Mathematics and Mathematical Statistics, have been recognised with the New Horizons Prize, awarded to outstanding early-career researchers.

Professor Suchitra Sebastian has been awarded the 2022 New Horizons in Physics Prize for high precision electronic and magnetic measurements that have profoundly changed our understanding of high temperature superconductors and unconventional insulators.

Professor Jack Thorne has been awarded the 2022 New Horizons in Mathematics Prize, for transformative contributions to diverse areas of algebraic number theory, and in particular for the proof, in collaboration with James Newton, of the automorphy of all symmetric powers of a holomorphic modular newform.

Professors Balasubramanian and Klenerman co-invented Solexa-Illumina Next Generation DNA Sequencing (NGS), technology that has enhanced our basic understanding of life, converting biosciences into ‘big science’ by enabling fast, accurate, low-cost and large-scale genome sequencing – the process of determining the complete DNA sequence of an organism’s make-up. They co-founded the company Solexa to make the technology available to the world.

̽��ֱ��benefits to society of rapid genome sequencing are huge. ̽��ֱ��almost immediate identification and characterisation of the virus which causes COVID-19, rapid development of vaccines, and real-time monitoring of new genetic variants would have been impossible without the technique Balasubramanian and Klenerman developed.

̽��ֱ��technology has had – and continues to have – a transformative impact in the fields of genomics, medicine and biology. One measure of the scale of change is that it has allowed a million-fold improvement in speed and cost when compared to the first sequencing of the human genome. In 2000, sequencing of one human genome took over 10 years and cost more than a billion dollars: today, the human genome can be sequenced in a single day at a cost of less than $1,000. More than a million human genomes are sequenced at scale each year, thanks to the technology co-invented by Professors Balasubramanian and Klenerman, meaning we can understand diseases much better and much more quickly. Earlier this year, they were awarded the Millennium Technology Prize. Balasubramanian is also based at the Cancer Research UK Cambridge Institute, and is a Fellow of Trinity College. Klenerman is a Fellow of Christ's College.

“Being awarded the New Horizons Prize is incredibly encouraging, uplifting and joyous,” said Sebastian. “It recognises a discovery made by our team of electrons doing what they're not supposed to do. It's gone from the moment of elation and disbelief at the discovery, and then trying to follow it through, when no one else quite thinks it’s possible or that it could be happening. It’s been an incredible journey, and having it recognised in this way is incredibly rewarding.”

Professor Jack Thorne is a number theorist in the Department of Pure Mathematics and Mathematical Statistics. One of the most significant open problems in mathematics is the Riemann Hypothesis, which concerns Riemann’s zeta function. Today we know that the zeta function is intimately tied up with questions concerning the statistical distribution of prime numbers, such as how many prime numbers there are, how closely they can be found on the number line. A famous episode in the history of the Riemann Hypothesis is Freeman Dyson’s observation that the zeroes of the zeta function appear to obey statistical laws arising from the theory of random matrices, which had first been studied in theoretical physics.

In 1916, during his time in Cambridge, Ramanujan wrote down an analogue of the Riemann zeta function, inspired by his work on the number of ways of expressing a given number as a sum of squares (a problem with a rich classical history), and made some conjectures as to its properties, which have turned out to be related to many of the most exciting developments in number theory in the last century. Actually, there are a whole family of zeta functions, the properties of which control the statistics of the sums of squares problem. Thorne's work, recognised in the prize citation, essentially shows for Ramanujan’s zeta functions what Riemann proved for his zeta function in 1859.

Taking a broader view, Ramanujan’s zeta functions are now seen to fit into the framework of the Langlands Program. This is a series of conjectures, made by Langlands in the 1960’s, which have been described as a “grand unified theory of mathematics”, and which can be used to explain any number of phenomena in number theory. Another famous example is Wiles proof, in 1994, of Fermat’s Last Theorem. Nowadays the essential piece of Wiles’ work is seen as progress towards a small part of the Langlands program. Thorne's work establishes part of Langlands’ conjectures for a class of objects including Ramanujan’s Delta function.

"I am deeply honoured to be awarded the New Horizons Prize for my work in number theory," said Thorne. "Number theory is a subject with a rich history in Cambridge and I feel very fortunate to be able to make my own contribution to this tradition."

For the tenth year, the Breakthrough Prize recognises the world’s top scientists. Each prize is US $3 million and presented in the fields of Life Sciences, Fundamental Physics (one per year) and Mathematics (one per year). In addition, up to three New Horizons in Physics Prizes, up to three New Horizons in Mathematics Prizes and up to three Maryam Mirzakhani New Frontiers Prizes are given out to early-career researchers each year, each worth US $100,000. ̽��ֱ��Breakthrough Prizes were founded by Sergey Brin, Priscilla Chan and Mark Zuckerberg, Yuri and Julia Milner, and Anne Wojcicki.

Four ̽��ֱ�� of Cambridge researchers – Professors Shankar Balasubramanian, David Klenerman, Suchitra Sebastian and Jack Thorne – have been recognised by the Breakthrough Prize Foundation for their outstanding scientific achievements.

L-R: Millennium Technology Prize, Nick Saffell, Jack Thorne

L-R: David Klenerman, Shankar Balasubramanian, Suchitra Sebastian, Jack Thorne

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̽��ֱ�� of Cambridge at the World Economic Forum 2016

cjb250 — Fri, 15 Jan 2016 10:56:46 +0000

̽��ֱ�� ̽��ֱ�� will host an IdeasLab looking at how breakthroughs in carbon reduction technologies will transform industries. IdeasLabs are quick-fire visual presentations followed by workgroup discussion, and have proved a successful format for engaging various communities in academic thinking.

Carbon Reduction Technologies: ̽��ֱ�� ̽��ֱ�� of Cambridge IdeasLab

Wednesday 20 January 16:15 - 17:30

Sir Leszek Borysiewicz, Vice-Chancellor, will introduce this event, which will look at how research by Cambridge academics has led to breakthroughs in carbon reduction technologies that will transform a range of industries. Ideas to be discussed include:

Decarbonizing industrial-scale processes using virtual avatars
Self-healing concrete for low-carbon infrastructure
Improving solar materials efficiency using quantum mechanics
Quantum materials for zero-loss transmission of electricity

̽��ֱ��event is supported Energy@Cambridge, a Strategic Research Initiative that brings together the activities of over 250 world-leading academics working in all aspects of energy-related research, covering energy supply, conversion and demand, across a wide range from departments.

̽��ֱ��speakers, all members of the Strategic Research Initiative, are:

Professor Abir Al-Tabbaa, Department of Engineering

Professor Al-Tabbaa is a Director of the Centre for Doctoral Training in Future Infrastructure and Built Environment. She leads international work on sustainable and innovative materials for construction and the environment. Her particular expertise relates to low-carbon and self-healing construction materials, ground improvement, soil mix technology and contaminated land remediation.

Professor Sir Richard Friend, Department of Physics

Professor Friend is the Director of the Maxwell Centre and the Winton Fund for the Physics of Sustainability. He is the lead academic on one of Energy@Cambridge’s Grand Challenges – Materials for Energy Efficient Information Communications Technology.

Professor Friend’s research encompasses the physics, materials science and engineering of semiconductor devices made with carbon-based semiconductors, particularly polymers. His research group was first to demonstrate using polymers efficient operation of field-effect transistors and light-emitting diodes. These advances revealed that the semiconductor properties of this broad class of materials are unexpectedly clean, so that semiconductor devices can both reveal their novel semiconductor physics, including their operation in efficient photovoltaic diodes, optically-pumped lasing, directly-printed polymer transistor circuits and light-emitting transistors.

Professor Markus Kraft, Department of Chemical Engineering and Biotechnology

Professor Kraft is the director of the Singapore-Cambridge CREATE Research Centre and a principal investigator of the Cambridge Centre for Carbon Reduction in Chemical Technology (C4T), one of the Grand Challenges. C4T is a world-leading partnership between Cambridge and Singapore, set up to tackle the environmentally relevant and complex problem of assessing and reducing the carbon footprint of the integrated petro-chemical plants and electrical network on Jurong Island in Singapore.

Professor Kraft has contributed to the detailed modelling of combustion synthesis of organic and inorganic nanoparticles. He has worked on fluidization, spray drying and granulation of fine powders. His interested include computational modelling and optimization targeted towards developing carbon abatement and emissions reduction technologies.

Dr Suchitra Sebastian, Department of Physics

Dr Sebastian creates and studies interesting quantum materials - often under extreme conditions such as very high magnetic and electric fields, enormous pressures, and very low temperatures - with a view to discovering unusual phases of matter. Among these are the family of superconductors - which have the exciting property of transporting electricity with no energy loss - and hence hold great promise for energy saving applications. One of her research programmes is to create a new generation of superconductors that operate at accessible temperatures, thus providing energy transmission and storage solutions of the future.

Will Science Save Us?

Friday 22 January

̽��ֱ��Vice Chancellor and Dr Suchitra Sebastian will take part in a lunchtime discussion entitled Will Science Save Us?, which will look at how we accelerate scientific breakthroughs that address society's greatest challenges.

* * *

̽��ֱ��World Economic Forum is an independent international organisation engaging business, political, academic and other leaders of society to shape global, regional and industry agendas; this year’s theme is ̽��ֱ��Reshaping of the World: Consequences for Society, Politics and Business.

̽��ֱ��Forum will provide an opportunity for the Cambridge researchers to engage with decision-makers in business, NGOs and in public policy, and to highlight new ideas from Cambridge in responding to global challenges.

For further information or to contact any of the speakers, please contact the team at Energy@Cambridge.

̽��ֱ��Vice Chancellor of the ̽��ֱ�� of Cambridge is to lead a delegation of academics to the annual meeting of the World Economic Forum at Davos, Switzerland, in January 2016, to explore issues including carbon reduction technologies and how science and engineering can best address society's greatest challenges.

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Coal Fired Power Station (cropped)

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To conduct, or to insulate? That is the question

sc604 — Thu, 02 Jul 2015 18:00:00 +0000

A new study has discovered mysterious behaviour of a material that acts like an insulator in certain measurements, but simultaneously acts like a conductor in others. In an insulator, electrons are largely stuck in one place, while in a conductor, the electrons flow freely. ̽��ֱ��results, published today (2 July) in the journal Science, challenge current understanding of how materials behave.

Conductors, such as metals, conduct electricity, while insulators, such as rubber or glass, prevent or block the flow of electricity. But by tracing the path that electrons follow as they move through a material, researchers led by the ̽��ֱ�� of Cambridge found that it is possible for a single material to display dual metal-insulator properties at once – although at the very lowest temperatures, it completely disobeys the rules that govern conventional metals. While it’s not known exactly what’s causing this mysterious behaviour, one possibility is the existence of a potential third phase which is neither insulator nor conductor.

̽��ֱ��duelling metal-insulator properties were observed throughout the interior of the material, called samarium hexaboride (SmB6). There are other recently-discovered materials which behave both as a conductor and an insulator, but they are structured like a sandwich, so the surface behaves differently from the bulk. But the new study found that in SmB6, the bulk itself can be both conductor and insulator simultaneously.

“ ̽��ֱ��discovery of dual metal-insulator behaviour in a single material has the potential to overturn decades of conventional wisdom regarding the fundamental dichotomy between metals and insulators,” said Dr Suchitra Sebastian of the ̽��ֱ��’s Cavendish Laboratory, who led the research.

In order to learn more about SmB6 and various other materials, Sebastian and her colleagues traced the path that the electrons take as they move through the material: the geometrical surface traced by the orbits of the electrons leads to a construction which is known as a Fermi surface. In order to find the Fermi surface, the researchers used a technique based on measurements of quantum oscillations, which measure various properties of a material in the presence of a high magnetic field to get an accurate ‘fingerprint’ of the material. For quantum oscillations to be observed, the materials must be as close to pure as possible, so that there are minimal defects for the electrons to bump into. Key experiments for the research were conducted at the National High Magnetic Field Laboratory in Tallahassee, Florida.

SmB6 belongs to the class of materials called Kondo insulators, which are close to the border between insulating and conducting behaviour. Kondo insulators are part of a larger group of materials called heavy fermion materials, in which complex physics arises from an interplay of two types of electrons: highly localised ‘f’ electrons, and ‘d’ electrons, which have larger orbits. In the case of SmB6, correlations between these two types of electrons result in insulating behaviour.

“It’s a dichotomy,” said Sebastian. “ ̽��ֱ��high electrical resistance of SmB6 reveals its insulating behaviour, but the Fermi surface we observed was that of a good metal.”

But the mystery didn’t end there. At the very lowest temperatures, approaching 0 degrees Kelvin (-273 Celsius), it became clear that the quantum oscillations for SmB6 are not characteristic of a conventional metal. In metals, the amplitude of quantum oscillations grows and then levels off as the temperature is lowered. Strangely, in the case of SmB6, the amplitude of quantum oscillations continues to grow dramatically as the temperature is lowered, violating the rules that govern conventional metals.

̽��ֱ��researchers considered several reasons for this peculiar behaviour: it could be a novel phase, neither insulator nor conductor; it could be fluctuating back and forth between the two; or because SmB6 has a very small ‘gap’ between insulating and conducting behaviour, perhaps the electrons are capable of jumping that gap.

“ ̽��ֱ��crossover region between two different phases – magnetic and non-magnetic, for example – is where the really interesting physics happens,” said Sebastian. “Because this material is close to the crossover region between insulator and conductor, we found it displays some really strange properties – we’re exploring the possibility that it’s a new quantum phase.”

Tim Murphy, the head of the National High Magnetic Field Laboratory’s DC Field Facility, where most of the research was conducted, said: “This work on SmB6 provides a vivid and exciting illustration of emergent physics resulting from MagLab researchers refining the quality of the materials they study and pushing the sample environment to the extremes of high magnetic fields and low temperatures.”

̽��ֱ��Cambridge researchers were funded by the Royal Society, the Winton Programme for the Physics of Sustainability, the European Research Council and the Engineering and Physical Sciences Research Council (UK).

Researchers have identified a material that behaves as a conductor and an insulator at the same time, challenging current understanding of how materials behave, and pointing to a new type of insulating state.

̽��ֱ��discovery of dual metal-insulator behaviour in a single material has the potential to overturn decades of conventional wisdom regarding the fundamental dichotomy between metals and insulators

Suchitra Sebastian

PhD student Maria Kiourlappou holding a piece of SmB6

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Superconducting secrets solved after 30 years

sc604 — Sun, 15 Jun 2014 17:00:00 +0000

Harnessing the enormous technological potential of high-temperature superconductors – which could be used in lossless electrical grids, next-generation supercomputers and levitating trains – could be much more straightforward in future, as the origin of superconductivity in these materials has finally been identified.

Superconductors, materials which can carry electric current with zero resistance, could be used in a huge range of applications, but a lack of understanding about where their properties originate from has meant that the process of identifying new materials has been rather haphazard.

Researchers from the ̽��ֱ�� of Cambridge have found that ripples of electrons, known as charge density waves or charge order, create twisted ‘pockets’ of electrons in these materials, from which superconductivity emerges. ̽��ֱ��results are published in the June 15th issue of the journal Nature.

Low-temperature, or conventional, superconductors were first identified in the early 20th century, but they need to be cooled close to absolute zero (zero degrees on the Kelvin scale, or -273 degrees Celsius) before they start to display superconductivity. So-called high-temperature superconductors however, can display the same properties at temperatures up to 138 Kelvin (-135 degrees Celsius), making them much more suitable for practical applications.

Since they were first identified in the mid-1980s, the process of discovering new high-temperature superconductors could be best described as random. While researchers have identified the ingredients that make for a good low-temperature superconductor, high-temperature superconductors have been more reluctant to give up their secrets.

In a superconductor, as in any electronic device, current is carried via the charge on an electron. What is different about superconductors is that the electrons travel in tightly bound pairs. When travelling on their own, electrons tend to bump into each other, resulting in a loss of energy. But when paired up, the electrons move smoothly through a superconductor’s structure, which is why superconductors can carry current with no resistance. As long as the temperature is kept sufficiently low, the electron pairs will keep moving through the superconductor indefinitely.

Key to conventional superconductors are the interactions of electrons with the lattice structure of the material. These interactions generate a type of ‘glue’ which holds the electrons together. ̽��ֱ��strength of the glue is directly related to the strength of the superconductor, and when the superconductor is exposed to an increase in temperature or magnetic field strength, the glue is weakened, the electron pairs break apart and superconductivity is lost.

“One of the problems with high-temperature superconductors is that we don’t know how to find new ones, because we don’t actually know what the ingredients are that are responsible for creating high-temperature superconductivity in the first place,” said Dr Suchitra Sebastian of the Cavendish Laboratory, lead author of the paper. “We know there’s some sort of glue which causes the electrons to pair up, but we don’t know what that glue is.”

In order to decode what makes high-temperature superconductors tick, the researchers worked backwards: by determining what properties the materials have in their normal, non-superconducting state, they might be able to figure out what was causing superconductivity.

“We’re trying to understand what sorts of interactions were happening in the material before the electrons paired up, because one of those interactions must be responsible for creating the glue,” said Dr Sebastian. “Once the electrons are already paired up, it’s hard to know what made them pair up. But if we can break the pairs apart, then we can see what the electrons are doing and hopefully understand where the superconductivity came from.”

Superconductivity tends to override other properties. For example, if in its normal state a superconductor was a magnet, suppressing that magnetism has been found to result in superconductivity. “So by determining the normal state of a superconductor, it would make the process of identifying new ones much less random, as we’d know what sorts of materials to be looking for in the first place,” said Dr Sebastian.

Working with extremely strong magnetic fields, the researchers were able to kill the superconducting effect in cuprates - thin sheets of copper and oxygen separated by more complex types of atoms.

Previous attempts to determine the origins of superconductivity by determining the normal state have used temperature instead of magnetic field to break the electron pairs apart, which has led to inconclusive results.

As cuprates are such good superconductors, it took the strongest magnetic fields in the world – 100 Tesla, or roughly one million times stronger than the Earth’s magnetic field – in order to suppress their superconducting properties.

These experiments were finally able to solve the mystery surrounding the origin of pockets of electrons in the normal state that pair to create superconductivity. It was previously widely held that electron pockets were located in the region of strongest superconductivity. Instead, the present experiments using strong magnetic fields revealed a peculiar undulating twisted pocket geometry -similar to Jenga bricks where each layer goes in a different direction to the one above or beneath it.

These results pinpointed the pocket locations to be where superconductivity is weakest, and their origin to be ripples of electrons known as charge density waves, or charge order. It is this normal state that is overridden to yield superconductivity in the family of cuprate superconductors studied.

“By identifying other materials which have similar properties, hopefully it will help us find new superconductors at higher and higher temperatures, even perhaps materials which are superconductors at room temperature, which would open up a huge range of applications,” said Dr Sebastian.

A breakthrough has been made in identifying the origin of superconductivity in high-temperature superconductors, which has puzzled researchers for the past three decades.

By identifying other materials which have similar properties, hopefully it will help us find new superconductors at higher and higher temperatures

Suchitra Sebastian

Nicolle R Fuller

Map of superconducting copper oxide structure.

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One step closer to the Holy Grail of physics

bjb42 — Wed, 16 Jul 2008 00:00:00 +0000

̽��ֱ��quest for room temperature superconductivity has gripped physics researchers since they saw the possibility more than two decades ago. Materials that could potentially transport electricity with zero loss (resistance) at room temperature hold vast potential; some of the possible applications include a magnetically levitated superfast train, efficient magnetic resonance imaging (MRI), lossless power generators, transformers, and transmission lines, powerful supercomputers, etc.

Unfortunately, scientists have been unable to decipher how copper oxide materials superconduct at extremely cold temperatures (such as that of liquid nitrogen), much less design materials that can superconduct at higher temperatures.

Materials that are known to superconduct at the highest temperatures are, unexpectedly, ceramic insulators that behave as magnets before 'doping' (the method of introducing impurities to a semiconductor to modify its electrical properties). Upon doping charge carriers (holes or electrons) into these parent magnetic insulators, they mysteriously begin to superconduct, i.e. the doped carriers form pairs that carry electricity without loss.

̽��ֱ��essential conundrum facing researchers in this area has been: how does a magnet that cannot transport electricity transform into a superconductor that is a perfect conductor of electricity? ̽��ֱ��Cambridge team have made a significant advance in answering this question.

̽��ֱ��researchers have discovered where the charge 'hole' carriers that play a significant role in the superconductivity originate within the electronic structure of copper-oxide superconductors. These findings are particularly important for the next step of deciphering the glue that binds the holes together and determining what enables them to superconduct.

Dr Suchitra E. Sebastian, lead author of the study, commented, "An experimental difficulty in the past has been accessing the underlying microscopics of the system once it begins to superconduct. Superconductivity throws a manner of 'veil' over the system, hiding its inner workings from experimental probes. A major advance has been our use of high magnetic fields, which punch holes through the superconducting shroud, known as vortices - regions where superconductivity is destroyed, through which the underlying electronic structure can be probed.

"We have successfully unearthed for the first time in a high temperature superconductor the location in the electronic structure where 'pockets' of doped hole carriers aggregate. Our experiments have thus made an important advance toward understanding how superconducting pairs form out of these hole pockets."

By determining exactly where the doped holes aggregate in the electronic structure of these superconductors, the researchers have been able to advance understanding in two vital areas:

(1) A direct probe revealing the location and size of pockets of holes is an essential step to determining how these particles stick together to superconduct.

(2) Their experiments have successfully accessed the region betwixt magnetism and superconductivity: when the superconducting veil is partially lifted, their experiments suggest the existence of underlying magnetism which shapes the hole pockets. Interplay between magnetism and superconductivity is therefore indicated - leading to the next question to be addressed.

Do these forms of order compete, with magnetism appearing in the vortex regions where superconductivity is killed, as they suggest? Or do they complement each other by some more intricate mechanism? One possibility they suggest for the coexistence of two very different physical phenomena is that the non-superconducting vortex cores may behave in concert, exhibiting collective magnetism while the rest of the material superconducts.

Scientists at the ̽��ֱ�� of Cambridge have identified a key component to unravelling the mystery of room temperature super-conductivity, according to a paper recently published in the scientific journal Nature.

A major advance has been our use of high magnetic fields, which punch holes through the superconducting shroud, known as vortices - regions where superconductivity is destroyed, through which the underlying electronic structure can be probed.

Dr Suchitra E. Sebastian

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CERN

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