Planckian metals have the potential to power high-temperature superconductors, quantum computers and a host of other next-generation technologies. However, these 鈥渟trange鈥 metals 鈥 in which electrical resistance increases linearly with temperature 鈥 are notoriously difficult to study, let alone comprehend.
In the last decade, physicists have attempted to explore the inner workings of these quantum materials with cold atom experiments, whereby the behavior of electrons is simulated with neutral atoms, light beams and ultra-cold temperatures. These 2D models provide an analog system that allows experimentalists to see the interactions at more scrutable length and time scales 鈥 microns and milliseconds, rather than angstroms and femtoseconds 鈥 bringing them ever closer to understanding the materials鈥 unusual electrical functions.
Now, Cornell researchers led by , professor of physics in the 麻豆视频 and 麻豆视频, have found this experimental model doesn鈥檛 capture what鈥檚 really happening inside strange metals at all.
Their paper, 鈥,鈥 published Oct. 25 in Physical Review B. The lead author is doctoral student Thomas Kiely.
鈥淭hese cold atom experiments are a really awesome way to try and learn about this strange metal behavior, this crazy unusual resistivity, which we believe is the key to understanding how to make higher-temperature superconductors and all sorts of other things,鈥 Mueller said. 鈥淲e found there鈥檚 actually a simple explanation for what happens in this experiment.鈥
Kiely and Mueller spent two years trying a variety of approaches to model the cold atom experiment. To visualize the experiment, imagine a Go board. The atoms are the black and white stones that can be moved, via quantum tunneling, from square to square, dissipating energy based on the strength of their interactions 鈥 or couplings 鈥 with other atoms.
The researchers found the most illuminating approach was to change the strength of the interactions between the atoms.
鈥淭his gives us a very clear picture of how to describe that system,鈥 Kiely said. 鈥淲hen the atoms interact with each other very weakly, we can kind of build in the effective interactions based on the fact that we know what鈥檚 going on when they鈥檙e not interacting.鈥
By locating the limit at which these interactions were the weakest, the researchers were able to observe the exotic behavior of strange metals, but, surprisingly, in a context that wasn鈥檛 strange enough to warrant it. And the behavior still could be quantitatively explained.
鈥淭he interpretation of the cold atom experiment was that the same physics that was responsible for these high-temperature superconductors was occurring in these analog experiments, that they had found a strange metal,鈥 Mueller said. 鈥淲hat Thomas showed was that although they saw the same thing as in the materials, it鈥檚 quite likely from a different source. This weakly attracting limit that we modeled is certainly not what鈥檚 going on in the material.鈥
While the Cornell researchers were able to explain with confidence what is happening in cold atom experiments, they are still not certain what is occurring inside strange metals themselves.
鈥淚t鈥檚 a hard problem,鈥 Mueller said. 鈥淲e鈥檙e hoping to have a more controlled setting to investigate the same physics, because the models that are being explored with these cold atom experiments probably aren鈥檛 sophisticated enough to explain what鈥檚 going on. But I think you can build a lot of great stuff off this, actually looking at this weak coupling limit and how things cross over into strong coupling.鈥
The research was supported by the National Science Foundation.
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