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>These “strange metals” have resistivity at low temperatures that is linearly proportional to temperature—that is, their resistivity varies with the actual tem

>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." Interesting... That could be worth further exploration!

chasil 3y ago
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.
- z2h-a6n 3y ago
  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 https://en.wikipedia.org/wiki/Drude_model [2]: https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f
z2h-a6n 3y ago
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.
- fuzzfactor 3y ago
  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.
peter_d_sherman 3y ago
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 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...)

chasil 3y ago

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.

z2h-a6n 3y ago
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 https://en.wikipedia.org/wiki/Drude_model [2]: https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f https://iopscience.iop.org/article/10.1088/1367-2630/ab4d0f

z2h-a6n 3y ago

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.

fuzzfactor 3y ago
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.

peter_d_sherman 3y ago

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 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...)