International Conference on Condensed Matter Physics
Calculations motivated by the successful prediction of the nickelate phase diagram suggest that palladates might hit the sweet spot for high-temperature superconductivity.
Copper-based (cuprate) superconductors have long held the record for the highest superconducting critical temperature (Tc) at ambient pressure. In 2019, after decades of theoretical and experimental effort, researchers reported a nickel-based (nickelate) analog to cuprate superconductors (see Trend: Entering the Nickel Age of Superconductivity). Since then, others have sought to pinpoint the factors that control superconductivity in such single-orbital-dominated systems. Motoharu Kitatani of the University of Hyogo in Japan and his colleagues now identify some of these factors and suggest that swapping out nickel for palladium could deliver a material that superconducts at even higher temperatures than cuprate superconductors [1]. The study could help guide the ongoing search for novel superconducting materials and establish “palladates” as the new kid on the block.
Kitatani and his colleagues previously had used a standard condensed-matter-physics model, called the single-band Hubbard model, to predict Tc for nickelates and had validated their predictions using measurements in defect-free nickelate films. Now, by simulating this system while varying the electrons’ interaction strength, filling factor, and energy-momentum dispersion, the researchers have tracked the strength of electron–electron pairing that leads to the emergence of superconductivity. This allows them to determine the electronic configuration that optimizes Tc. However, according to their results, neither nickelates nor cuprates come close to these optimized conditions. Instead, the researchers have found that palladates, thanks to somewhat weaker interactions and thus weaker correlations, could more closely approach the optimal “Goldilocks” conditions that maximize Tc. The researchers hope their theoretical results will encourage experimentalists to grow and examine palladates as new candidates for higher-Tc options.
A density wave (DW) is a fundamental type of long-range order in quantum matter tied to self-organization into a crystalline structure. Although density waves are seen in a wide range of materials, such as metals, insulators, and superconductors, studying them has proven challenging, particularly when this order (the patterns of the wave’s particles) coexists with other types of organization, such as superfluidity, which allows particles to flow without resistance. Scientists at EPFL have found a new way to create a “density wave” in an atomic gas. The findings could lead to a better understanding of the behavior of quantum matter. Professor Jean-Philippe Brantut at EPFL said, “Cold atomic gases were well known in the past for the ability to ‘program’ the interactions between atoms. Our experiment doubles this ability!” To study this interaction, Brantut, and his colleagues created a “unitary Fermi gas,” a thin gas of lithium atoms that has been cooled to incredibly low temperatu...
International Conference on Condensed Matter Physics E=mc2 Albert Einstein proposed the most famous formula in physics in a 1905 paper on Special Relativity titled Does the inertia of an object depend upon its energy content? Essentially, the equation says that mass and energy are intimately related. Atom bombs and nuclear reactors are practical examples of the formula working in one direction, turning matter into energy. But until now there has been no way to do the reverse, turn energy into matter. What makes it particularly hard is that c2 term, the speed of light squared. It accounts for the huge amounts of energy released in nuclear reactions, and the huge amount you’d need to inject to turn energy into matter. Previous experiments have always required a little bit of mass, even if it was only an electron’s worth. But scientists at Imperial College London (including a visiting physicist from Germany's Max Planck Institute for Nuclear Physics) think they’ve figured out how to...
Of all the science-fiction-sounding names that have come to fruition in recent years, perhaps none is as mysterious or seemingly fictitious as time crystals. The name evokes something between Back to the Future and Donnie Darko, and the reality is perhaps crazier than either. Two separate groups of scientists recently reported they observed time crystals, which lends credence to the idea that this theoretical state of matter is something humans can actually create and observe. And indeed, time crystals can be grown in a child’s bedroom. But, it requires nuclear sensors and lasers to help time crystals reach their full potential and then measure and observe them. This combination of dramatic scientific terms and shockingly simple objects is a great analogy for time crystals as a whole. Read on to understand what they are and how they might affect our lives. What Are Time Crystals? Time crystals are systems of atoms that arrange themselves in time the way more traditional solids cr...
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