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An international team of researchers led by Paul Scherrer Institute postdoctoral researcher Niels Schröter now provide an important benchmark for how "strong" topological phenonena can be in a real material. Writing in Science, the team reports experiments in which they observed that, in the topological semimetal palladium gallium (PdGa), one of the most common classifiers of topological phenomena, the Chern number, can reach the maximum value that is allowed in any metallic crystal. That this is possible in a real material has never been shown before. Moreover, the team has established ways to control the sign of the Chern number, which might bring new opportunities for exploring, and exploiting, topological phenomena. Illinois Physics Professor Barry Bradlyn contributed to the theoretical work elucidating the team's experiments.

At the European Organization for Nuclear Research (CERN), over 200 physicists across dozens of institutions are collaborating on a project called COMPASS. This experiment (short for Common Muon and Proton Apparatus for Structure and Spectroscopy) uses CERN’s Super Proton Synchrotron to tear apart protons with a particle beam, allowing researchers to see the subatomic quarks and gluons that make up these building blocks of the universe. But particle beams aren’t the only futuretech in play – the experiments are also enabled by a heavy dose of supercomputing power.

New findings from physicists at the University of Illinois, in collaboration with researchers at The University of Tokyo and others, clarify the physics of coupling topological materials with simple, conventional superconductors.

Through a novel method they devised to fabricate bulk insulating topological insulator (TI) films on superconductor (SC) substrates, the researchers were able to more precisely test the proximity effect, or coupling when two materials contact one another, between TIs and SCs. They found that when the TI film is bulk insulating, no superconductivity is observed at the top surface, but if it is a metal, as in prior work, strong, long-range superconducting order is seen. The experimental efforts were led by physics Professor Tai-Chang Chiang and Joseph Andrew Hlevyack, postdoctoral researcher in Professor Chiang’s group, in collaboration with Professor James N. Eckstein’s group including Yang Bai, Professor Kozo Okazaki’s Lab at The U. of Tokyo, and five other institutes internationally. The findings are published in Physical Review Letters, which has been highlighted as a PRL Editors’ Suggestion.

  • Accolades

Illinois Physics Assistant Professor Barry Bradlyn has been selected for a 2020 National Science Foundation CAREER (Faculty Early Career Development) Award. This award is conferred annually in support of junior faculty who excel in the role of teacher-scholars by integrating outstanding research programs with excellent educational programs. Receipt of this award also reflects great promise for a lifetime of leadership within the recipients’ respective fields.

Bradlyn is a theoretical condensed matter physicist whose work studying the novel quantum properties inherent in topological insulators and topological semimetals has already shed new light on these extraordinary systems. Among his contributions, he developed a real-space formulation of topological band theory, allowing for the prediction of many new topological insulators and semimetals.

  • In the Media

The shocking death of George Floyd is unfortunately not a singular event in the United States. Eric Garner, Michael Br own, Freddie Gray, Amadou Diallo (1), and Breonna Taylor (2) are just a few examples from a long list of unarmed Black people who have died at the hands of the police. This pattern of violence is deeply rooted in the history of Black-White relations in the United States and the failure of the leaders of this country to deal with systemic racism. As professional physicists, we suggest that professional science and humanities organizations such as the American Physical Society (APS) take action by refusing to hold conferences in cities where police brutality takes place.

  • Research
In biology, phylogenetic trees represent the evolutionary history and diversification of species – the “family tree” of Life. Phylogenetic trees not only describe the evolution of a group of organisms but can also be constructed from the organisms within a particular environment or ecosystem, such as the human microbiome. In this way, they can describe how this ecosystem evolved and what its functional capabilities might be.

Now, researchers at Illinois have presented a new analysis of the patterns generated by phylogenetic trees, suggesting that they reflect previously hypothesized connections between evolution and ecology. The study was led by Swanlund Professor of Physics Nigel Goldenfeld (BCXT leader/GNDP), with team members graduate student Chi Xue and former undergraduate student Zhiru Liu, now at Stanford University. Their findings were published in a recent article in the journal Proceedings of the National Academy of Science, titled “Scale-invariant topology and bursty branching of evolutionary trees emerge from niche construction.”

  • Research

The charge of a single electron, e, is defined as the basic unit of electric charge. Because electrons—the subatomic particles that carry electricity—are elementary particles and cannot be split, fractions of electronic charge are not normally encountered. Despite this, researchers at the University of Illinois at Urbana-Champaign have recently observed the signature of fractional charges ranging from e/4 to 2e/3 in exotic materials known as topological crystalline insulators.

The team of researchers, led by Illinois Mechanical Science and Engineering Professor Gaurav Bahl and Illinois Physics Professor Taylor Hughes, has been using ultra high frequency electric circuits to study topological insulators since 2017. Their recent measurement of fractional charge, appearing in the current issue of the journal Science, stems from the team’s theoretical work on crystalline insulators.

Find out how you can shine with solar energy, even if you do not always get direct sunlight. In this discussion with an Illinois Solar Energy Association Solar Ambassador, you will learn:

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  • Resources for finding reputable installers
  • In the Media
  • Research

The theory behind dark matter detection dates back to a 1985 paper that considered how a neutrino detector could be repurposed to look for particles of the substance. The study proposed that an incoming dark matter particle could hit an atomic nucleus in the detector and give it a kick—similar to one billiard ball crashing into another. This collision would transfer momentum from the dark matter, walloping the nucleus hard enough to make it spit out an electron or a photon.

At high energies, this picture is essentially fine. Atoms in the detector can be thought of as free particles, discrete and unconnected to one another. At lower energies, however, the picture changes.

“Your detectors are not made of free particles,” says Yonatan (Yoni) Kahn, a dark matter theorist at the University of Illinois at Urbana-Champaign and a co-author of the first paper. “They’re just made of stuff. And you have to understand the stuff if you want to understand how your detector actually works.”

For decades, scientists studying the muon have been puzzled by a strange pattern in the way muons rotate in magnetic fields, one that left physicists wondering if it can be explained by the Standard Model — the best tool physicists have to understand the universe.

This week, an international team of more than 170 physicists published the most reliable prediction so far for the theoretical value of the muon’s anomalous magnetic moment, which would account for its particular rotation, or precession. The magnetic moment of subatomic particles is generally expressed in terms of the dimensionless Landé factor, called g. While a number of international groups have worked separately on the calculation, this publication marks the first time the global theoretical physics community has come together to publish a consensus value for the muon’s magnetic moment.

  • In the Media

Walking to school as a child, UC San Diego visiting professor Smitha Vishveshwara asked her father, a black hole physicist, what he did for a living.

“He’d say, ‘Oh, I show that you can’t really kick a black hole.’ He’d be very playful,” said Vishveshwara, who lives in Solana Beach. “What he really meant was that he showed that black holes were stable entities.”

Through her father’s work, she learned about Margaret Burbidge, an influential astronomer, astrophysicist and the first director of UC San Diego’s Center for Astrophysics and Space Sciences. Coming full circle, Vishveshwara now serves as the university’s Margaret Burbidge visiting professor of physics.

  • Education

When Physics senior lecturer Eugene Colla begins remotely teaching his Modern Experimental Physics course in June, he’ll be ready. Colla and his co-instructor, Prof. Virginia (Gina) Lorenz, collaborated with physics teaching lab specialist, Jack Boparai, and a team of teaching assistants to successfully convert the course to virtual instruction midway through spring semester in response to COVID-19.

Online conversion was no small feat for Colla, who has taught Physics 403 since 2004 and has watched the class size more than double in that time. The spring semester saw 28 students, including three exchange students from the United Kingdom.

  • Research Funding

The Gordon and Betty Moore Foundation, through its Emergent Phenomena in Quantum Systems Initiative (EPiQS), has awarded substantial research funding to two experimental condensed matter physicists at the University of Illinois at Urbana-Champaign. Physics Professors Peter Abbamonte and Vidya Madhavan will receive EPiQS Experimental Investigator awards of $1.6 million each over the next five years.

EPiQS prioritizes high-risk, high-reward fundamental research programs in quantum materials, to foster scientific breakthroughs. EPiQS experimental investigators have the freedom to pursue challenging and novel research directions of the scientists’ own choosing.

  • research

Researchers from the University of Illinois at Urbana-Champaign’s Grainger College of Engineering have experimentally demonstrated a new way to transport energy even through wave-guides that are defective and even if the disorder is a transient phenomenon in time. This work could lead to much more robust devices that continue to operate in spite of damage.

Gaurav Bahl, associate professor in mechanical science and engineering, and Taylor Hughes, physics professor, published their findings in Nature Communications. This important work was led by postdoctoral researcher Inbar Grinberg, also in mechanical science and engineering.

  • In the Media

Neither Goldenfeld nor Maslov had advised policymakers before. A 63-year-old bespectacled theorist originally from the UK, Goldenfeld began his research career studying superconductors and polymers. Over more than three decades at UIUC, he had branched into computational biology to study flocking and evolutionary patterns in various ecosystems, among other research interests.

Maslov, a 51-year-old Russian-American who kept his hair long even prior to the pandemic, followed a similarly interdisciplinary academic career. Skipping around from magnetic materials to financial statistics to microbial ecology, the theorist arrived at UIUC in 2015 after nearly two decades at Brookhaven National Laboratory. As members of the same research team, they frequently chatted. “Our offices are right next to each other,” says Maslov. Both are APS Fellows and Goldenfeld is the winner of this year's APS Leo Kadanoff Prize.