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.
International Conference on Condensed Matter Physics Researchers from the Institute of Theoretical Physics (ITP) of the Chinese Academy of Sciences (CA S) and Shanghai Jiao Tong University (SJTU) have found that granular matter (such as sand) and some black hole models display similar nonlinear effects. The bridge between the two is the holographic duality. Holographic duality allows one to map unsolved physical problems to tractable higher-dimensional gravitational counterparts and vice versa. The mapping between different dimensions resembles the optical holographic projection technique, hence the name. Although the holographic duality originated from string theory and was part of the quest for a consistent theory of quantum gravity, it has also been widely applied to quantum chromodynamics, condensed matter physics, and quantum information. In this work, the idea of holographic duality is extended to a concrete type of athermal, disordered solids—granular materials. Sinc...
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...
International Conference on Condensed Matter Physics In a historic achievement, University of Rochester researchers have created a superconducting material at both a temperature and pressure low enough for practical applications. "With this material, the dawn of ambient superconductivity and applied technologies has arrived," according to a team led by Ranga Dias, an assistant professor of mechanical engineering and physics. In a paper in Nature, the researchers describe a nitrogen-doped lutetium hydride (NDLH) that exhibits superconductivity at 69 degrees Fahrenheit (20.5 degrees Celsius) and 10 kilobars (145,000 pounds per square inch, or psi) of pressure. Although 145,000 psi might still seem extraordinarily high (pressure at sea level is about 15 psi), strain engineering techniques routinely used in chip manufacturing, for example, incorporate materials held together by internal chemical pressures that are even higher. Scientists have been pursuing this breakthrough in c...
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