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Scientists at the Max Planck Institute for Chemical Physics of Solids in Dresden, Princeton University, the University of Illinois at Urbana-Champaign, and the University of the Chinese Academy of Sciences have spotted the fingerprint of an elusive particle: The axion—first predicted 42 years ago as an elementary particle in extensions of the standard model of particle physics. Based on predictions from Illinois Physics Professor Barry Bradlyn and Princeton Physics Professor Andrei Bernevig's group, the group of Chemical Physics Professor Claudia Felser at Max Planck in Dresden produced the charge density wave Weyl metalloid (TaSe4)2I and investigated the electrical conduction in this material under the influence of electric and magnetic fields. It was found that the electric current in this material below -11 °C is actually carried by axion particles.

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  • Urbana Style

Physics Professor Smitha Vishveshwara has been elected a Fellow of the American Physical Society (APS) “for pioneering theory of quantum dynamics in nonequilibrium systems and novel phenomena in cold Bose gases.”

Vishveshwara is a theoretical condensed matter physicist with broad research interests in non-equilibrium and strongly correlated systems at all scales, from subatomic to cosmic. A common thread throughout her work is the characterization of emergent phenomena in quantum states of matter—including superconductivity, superfluidity, Mott insulators, topological systems, fractional quantum Hall states, and Majorana wires. In true “Urbana style,” Vishveshwara’s collaborations at Illinois and beyond, often involving close rapport with experimental colleagues, have produced viable experimental stratagems and identified clear signatures that characterize particular states of matter.

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One of the greatest mysteries in condensed matter physics is the exact relationship between charge order and superconductivity in cuprate superconductors. In superconductors, electrons move freely through the material—there is zero resistance when it’s cooled below its critical temperature. However, the cuprates simultaneously exhibit superconductivity and charge order in patterns of alternating stripes. This is paradoxical in that charge order describes areas of confined electrons. How can superconductivity and charge order coexist?  

Now researchers at the University of Illinois at Urbana-Champaign, collaborating with scientists at the SLAC National Accelerator Laboratory, have shed new light on how these disparate states can exist adjacent to one another. Illinois Physics post-doctoral researcher Matteo Mitrano, Professor Peter Abbamonte, and their team applied a new x-ray scattering technique, time-resolved resonant soft x-ray scattering, taking advantage of the state-of-the-art equipment at SLAC. This method enabled the scientists to probe the striped charge order phase with an unprecedented energy resolution. This is the first time this has been done at an energy scale relevant to superconductivity.

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Illinois Physics Professor Philip Phillips and Math Professor Gabriele La Nave have theorized a new kind of electromagnetism far beyond anything conceivable in classical electromagnetism today, a conjecture that would upend our current understanding of the physical world, from the propagation of light to the quantization of charge. Their revolutionary new theory, which Phillips has dubbed “fractional electromagnetism,” would also solve an intriguing problem that has baffled physicists for decades, elucidating emergent behavior in the “strange metal” of the cuprate superconductors.

This research is published in an upcoming colloquium paper in Reviews of Modern Physics (arXiv:1904.01023v1).

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Researchers at the Paul Scherrer Institute in Switzerland working with scientists at institutions in Germany, Great Britain, Spain, and the US, have investigated a novel crystalline material, a chiral semimetal, exhibiting never-before-seen electronic properties. These include so-called chiral Rarita-Schwinger fermions in the interior and very long, quadruple topological Fermi arcs on the surface. The crystal, synthesized at the Max Planck Institute for Chemical Physics of Solids in Dresden, Germany, comprises aluminum and platinum atoms arranged in a helical pattern, like a spiral staircase. It’s the crystal’s chiral symmetry that hosts exotic emergent electronic properties.

These research findings, published online in the journal Nature Physics on May 6, 2019, validate a 2016 theoretical prediction by University of Illinois Physics Professor Barry Bradlyn (then a postdoc at the Princeton Center for Theoretical Science), et al., in the journal Science (vol. 353, no. 6299, aaf5037). That theoretical work was subsequently rounded out by a team of physicists at Princeton University, in research published in 2017 and 2018.

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University of Illinois at Urbana-Champaign Emeritus and Research Professor of Physics Tai-Chang Chiang has been selected for the 2019 Arthur H. Compton Award of the Advanced Photon Source Users Organization (APSUO). The award recognizes a significant scientific or technical accomplishment at the Advanced Photon Source (APS), a national synchrotron-radiation light source research facility housed at Argonne National Laboratory and funded by the US Department of Energy’s Office of Science. The award will be presented to Chiang at the APS/CNM User Meeting in early May.

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Professor Nadya Mason has been elected a Fellow of the American Physical Society (APS) "for seminal contributions to the understanding of electronic transport in low dimensional conductors, mesoscopic superconducting systems, and topological quantum materials."

Mason is an experimental condensed matter physicist who has earned a reputation for her deep-sighted and thorough lines of attack on the most pressing problems in strongly correlated nanoscale physics.

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Recently, a team of scientists led by Pablo Jarillo-Herrero at the Massachusetts Institute of Technology (MIT) created a huge stir in the field of condensed matter physics when they showed that two sheets of graphene twisted at specific angles—dubbed “magic-angle” graphene—display two emergent phases of matter not observed in single sheets of graphene. Graphene is a honeycomb lattice of carbon atoms—it’s essentially a one-atom-thick layer of graphite, the dark, flaky material in pencils. 

Researchers at the University of Illinois at Urbana-Champaign have recently shown that the insulating behavior reported by the MIT team has been misattributed. Professor Philip Phillips, a noted expert in the physics of Mott insulators, says a careful review of the MIT experimental data by his team revealed that the insulating behavior of the “magic-angle” graphene is not Mott insulation, but something even more profounda Wigner crystal.

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Now, a novel sample-growing technique developed at the U. of I. has overcome these obstacles. Developed by physics professor James Eckstein in collaboration with physics professor Tai-Chang Chiang, the new “flip-chip” TI/SC sample-growing technique allowed the scientists to produce layered thin-films of the well-studied TI bismuth selenide on top of the prototypical SC niobium—despite their incompatible crystalline lattice structures and the highly reactive nature of niobium.

These two materials taken together are ideal for probing fundamental aspects of the TI/SC physics, according to Chiang: “This is arguably the simplest example of a TI/SC in terms of the electronic and chemical structures. And the SC we used has the highest transition temperature among all elements in the periodic table, which makes the physics more accessible. This is really ideal; it provides a simpler, more accessible basis for exploring the basics of topological superconductivity,” Chiang comments.

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Researchers have produced a “human scale” demonstration of a new phase of matter called quadrupole topological insulators that was recently predicted using theoretical physics. These are the first experimental findings to validate this theory.

The researchers report their findings in the journal Nature.

The team’s work with QTIs was born out of the decade-old understanding of the properties of a class of materials called topological insulators. “TIs are electrical insulators on the inside and conductors along their boundaries, and may hold great potential for helping build low-power, robust computers and devices, all defined at the atomic scale,” said mechanical science and engineering professor and senior investigator Gaurav Bahl.

The uncommon properties of TIs make them a special form of electronic matter. “Collections of electrons can form their own phases within materials. These can be familiar solid, liquid and gas phases like water, but they can also sometimes form more unusual phases like a TI,” said co-author and physics professor Taylor Hughes.

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On Thursdays throughout the semester, staff writer Adalberto Toledo will book an appointment with a UI professor. Today: physics professor NADYA MASON, director of the new Materials Research Science and Engineering Center.

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Excitonium has a team of researchers at the University of Illinois at Urbana-Champaign… well… excited! Professor of Physics Peter Abbamonte and graduate students Anshul Kogar and Mindy Rak, with input from colleagues at Illinois, University of California, Berkeley, and University of Amsterdam, have proven the existence of this enigmatic new form of matter, which has perplexed scientists since it was first theorized almost 50 years ago.

The team studied non-doped crystals of the oft-analyzed transition metal dichalcogenide titanium diselenide (1T-TiSe2) and reproduced their surprising results five times on different cleaved crystals. University of Amsterdam Professor of Physics Jasper van Wezel provided crucial theoretical interpretation of the experimental results.

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The American Chemical Society (ACS), through its Division of History of Chemistry, has an award that acknowledges these greatest of strides: the Chemical Breakthrough Awards are presented annually in recognition of “seminal chemistry publications, books, and patents that have been revolutionary in concept, broad in scope, and long-term in impact.” These awards are made to the department where the breakthrough occurred, not to the individual scientists or inventors.

This year, the ACS honored the discovery of “J-coupling” (also known as spin-spin coupling) in liquids, a breakthrough that enabled scientists to use Nuclear Magnetic Resonance (NMR) spectroscopy to identify atoms that are joined by a chemical bond and so to determine the structure of molecules.

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Innovative materials are the foundation of countless breakthrough technologies, and the Illinois Materials Research Science and Engineering Center will develop them. The new center is supported by a six-year, $15.6 million award from the National Science Foundation’s Materials Research Science and Engineering Centers program. It is led by U of I Professor of Physics Nadya Mason and will be situated in the Frederick Seitz Materials Research Laboratory, part of the Department of Physics complex. 

 

The Illinois Materials Research Science and Engineering Center will build highly interdisciplinary teams of researchers and students to study two types of materials. One research group will study new magnetic materials, where ultra-fast magnetic switching could form the basis of smaller, more robust magnetic memory storage. The second group will design materials that can withstand bending and crumpling that typically destroys the properties of those materials—and will even create materials where crumpling enhances performance. This would enable materials in better contact with our bodies, because our limbs, skin, and even cells bend and move dynamically at both the macro- and microscale. In this way, such materials can form the basis of wearable electronics or medical devices that interface with, conform to, and move with our bodies.

 

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Quanta Magazine recently spoke with Goldenfeld about collective phenomena, expanding the Modern Synthesis model of evolution, and using quantitative and theoretical tools from physics to gain insights into mysteries surrounding early life on Earth and the interactions between cyanobacteria and predatory viruses. A condensed and edited version of that conversation follows.