Quantum Weirdness in New Metals Bends the Rules of Physics(scientificamerican.com)
scientificamerican.com
Quantum Weirdness in New Metals Bends the Rules of Physics
https://www.scientificamerican.com/article/quantum-weirdness-in-new-strange-metals-bends-the-rules-of-physics/
15 comments
Also, there apparently is something called "Constantan" -- a metal compound (usually) made from 55% Copper and 45% Nickel (at least according to Wikipedia):
https://en.wikipedia.org/wiki/Constantan
>"Its main feature is the low thermal variation of
its resistivity, which is constant over a wide range of temperatures."
In other words, NOT a square relationship nor even a linear one(!) -- in the temperature range where Constantan's resistivity is constant...
(At least, according to Wikipedia...)
https://en.wikipedia.org/wiki/Constantan
>"Its main feature is the low thermal variation of
its resistivity, which is constant over a wide range of temperatures."
In other words, NOT a square relationship nor even a linear one(!) -- in the temperature range where Constantan's resistivity is constant...
(At least, according to Wikipedia...)
And I think it implies that strange metals are not Landau Fermi liquids:
>Almost 70 years ago Russian physicist Lev Landau and his collaborators introduced an incredibly successful conjecture, now known as Landau Fermi liquid theory, to try to understand electron interactions within metals.
>Physicists have discovered an entire zoo of quasiparticles in solid materials with names such as phonons, magnons, spinons, holons and plasmons.
>By thinking of the collective actions of electrons as quasiparticles, physicists have made testable predictions that have been verified time and again in experiments on metals such as gold, silver, copper and aluminum.
>In recent years physicists have found a dozen or more materials that are clearly metals, in the sense that their electrical resistivity decreases with decreasing temperature, but that are not Fermi liquids. These “strange metals” have resistivity at low temperatures that is linearly proportional to temperature—that is, their resistivity varies with the actual temperature rather than with the square of the temperature.
>Scientists have observed superconductivity emerging in multiple families of strange metals at relatively high temperatures.
>Almost 70 years ago Russian physicist Lev Landau and his collaborators introduced an incredibly successful conjecture, now known as Landau Fermi liquid theory, to try to understand electron interactions within metals.
>Physicists have discovered an entire zoo of quasiparticles in solid materials with names such as phonons, magnons, spinons, holons and plasmons.
>By thinking of the collective actions of electrons as quasiparticles, physicists have made testable predictions that have been verified time and again in experiments on metals such as gold, silver, copper and aluminum.
>In recent years physicists have found a dozen or more materials that are clearly metals, in the sense that their electrical resistivity decreases with decreasing temperature, but that are not Fermi liquids. These “strange metals” have resistivity at low temperatures that is linearly proportional to temperature—that is, their resistivity varies with the actual temperature rather than with the square of the temperature.
>Scientists have observed superconductivity emerging in multiple families of strange metals at relatively high temperatures.
That is the common interpretation in the field, and in fact the phrases "strange metal" and "non-Fermi-liquid" are used somewhat interchangeably.
I'd point out that there is another interpretation of resistivity that is linear in temperature, namely that the basic physics of electron transport [1] is the same as a standard metal, where the scattering rate (proportional to resistivity) is proportional to temperature squared. The difference from normal metals is attributed to the linear increase in the carrier concentration (e.g. density of free electrons) with temperature. Since the carrier concentration (in the simple model) is inversely proportional to resistivity, this partially cancels the T^2 dependence of the scattering rate and produces T-linear resistivity. This is not (yet?) widely accepted in the literature, and I doubt it can explain all T-linear resistivity, but I think there's fairly strong evidence to believe it could explain some instances of T-linear resistivity, e.g. in the cuprates [2]. (n.b. I'm academically associated with some of the proponents of this idea, though I'm personally somewhat agnostic on the matter.)
[1]: https://en.wikipedia.org/wiki/Drude_model [2]: https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f
I'd point out that there is another interpretation of resistivity that is linear in temperature, namely that the basic physics of electron transport [1] is the same as a standard metal, where the scattering rate (proportional to resistivity) is proportional to temperature squared. The difference from normal metals is attributed to the linear increase in the carrier concentration (e.g. density of free electrons) with temperature. Since the carrier concentration (in the simple model) is inversely proportional to resistivity, this partially cancels the T^2 dependence of the scattering rate and produces T-linear resistivity. This is not (yet?) widely accepted in the literature, and I doubt it can explain all T-linear resistivity, but I think there's fairly strong evidence to believe it could explain some instances of T-linear resistivity, e.g. in the cuprates [2]. (n.b. I'm academically associated with some of the proponents of this idea, though I'm personally somewhat agnostic on the matter.)
[1]: https://en.wikipedia.org/wiki/Drude_model [2]: https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f
The understanding of strange metals, and more broadly, systems (i.e. materials) where strong (often quantum) interactions are important is one of the main general research areas of modern physics. This is motivated partly by the interest in understanding the fundamental physics involved, and partly because these strongly-interacting systems often have other interesting properties such as high-temperature supeconductivity, or various magnetic properties that may be useful for quantum computing. It's a large and active area of research.
Maybe the rules of physics need to have a measure of "ductility" all their own.
So they don't get really bent out of shape ;)
I know what I would be doing with an alloy like that.
So they don't get really bent out of shape ;)
I know what I would be doing with an alloy like that.
> bends OUR rules of physics.
>THE rules of physics are still up for discovery.
THE rules of physics are OUR approximation of how we understand the physical reality we live in. They are a human invention to describe a existing system, and thus the "our" is implied.
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Exactly. Too many people still act as if everything had already been discovered, was known and fully understood.
And as a result, new findings or solutions are often ignored, instead of used for the benefit of all.
And as a result, new findings or solutions are often ignored, instead of used for the benefit of all.
This seems like a non-sequitur. I don't see that there's any way to interpret the title that doesn't imply there are new discoveries in the laws of physics.
Yes, THE laws of physics pretty clearly refers to OUR laws of physics in this context. There is no other law. There will never be any absolute truth to be considered THE law of physics, only ever the models we contrive.
Minor but perhaps significant nitpick: the title of the article is "Quantum Weirdness in New Strange Metals Bends the Rules of Physics", and in this case "Strange Metal" is a technical term. If the title is to be edited for length or clickbait-minimization, I would recommend removing the word "New", since the start of this story is at least ~38 years old, possibly older.
Also it’s backwards titled, since it is bending our understanding of the rules of Physics.
their resistivity varies with the actual temperature rather than with the square of the temperature."
Interesting...
That could be worth further exploration!