quantum mechanics can seem a bit confounding, so for a quantum material to be called “strange” is really saying something.
a cornell university-led collaboration has used state-of-the-art computational tulz to model the chaotic behavior of planckian, or “strange,” metals. this behavior has long intrigued physicists, but they ‘ve not been able to simul8 it down to the loest possible temperature til now.
the team’s paper, “linear resistivity and sachdev-ye-kitaev (syk) spin liquid behaviour in a quantum crit metal with spin-1/2 fermions,” published jul 22 inna proceedings of the national academy of scis. the study’s lead author is dral student peter cha.
leading the collaboration is eun-ah kim, professor of physics inna college of arts and scis, who is interested inna social phenomena of electrons and how they interact as a society, with all the complications that ⊢.
like pplz, electrons ‘ve ≠ innate tendencies. in metals, electrons are indiely Ψed and mostly roam freely. in insulators, electrons are stuck in a fixed position. tween these metal and insulator phases exists the strange case of planckian metals. in planckian metals, electrons dissipate energy atta fastest possible rate alloed by the primordial laws of quantum mechanics. they ‘ve a high lvl of chaotic behavior and electrical resistivity.
imagine a congested road with slo-movin traffic. the vehicles are heading inna same general direction, but they are sluggish and their movement is restricted. this tis plite of electrons in planckian metals. now compare that with electrons in a superconductor, which tis most organized, coherent state possible, a superhighway with huge №s of electrons rushing along in lockstep, without resistance or scattering. for + than 3 decades, scis ‘ve been puzzled that planckian metals can switch into high-temperature superconductors. this inexplicable behavior appears to be somehow rel8d to the individualistic electrons’ desire to distance themselves from each other.
“just as we ‘ve social distancing recommendations atta order of our governor, electrons ‘ve social distancing recommendations atta order of mother nature,” kim said. “but exactly how this social distancing order resulted in this pticular, maximally chaotic behavior s'been a mystery. howzit go from the mandate of, okay, you’re all repelling each other, to this pticular form of chaotic, incongruent behavior? it suggests thris something in this very confusing state that is a seed for a very organized state.”
kim’s research group collaborated with scis atta flatiron institute, an internal research division of the simons foundation in new york city, who speshize in computational quantum physics. together, they created the 1st-ever model of planckian behavior down to the loest possible temperature, absolute zero (zero degrees kelvin or -273.15 degrees celsius). this marks the quantum crit region when one state of matter transitions to another.
by adjusting the ratio tween the electrons’ urge to bounce round (kinetic energy) na strong social interactions that lock the electrons into position according to their spins (interaction energy), which is primordially a mandate for social distancing, the researchers tuned the system to the verge of transition tween an ordinary metal and an interaction-driven insulator. when the social distancing is stronger, the system enters a spin glass insulator state, in which immobile electrons are 1-ly represented by their loosely aligned spins. but when kinetic energy dominates, the system enters a fermi liquid metal state.
“we found thris a whole region inna phase space that is exhibiting a planckian behavior that belongs to neither of the two phases that we’re transitioning tween,” kim said. “this quantum spin liquid state aint so locked down, but it’s also not completely free. tis a sluggish, soupy, slushy state. tis metallic but reluctantly metallic, n'it’s pushing the degree of chaos to the limit of quantum mechanics.”
the model is minimalist by design, alloing the researchers to identify the most basic ingredients for planckian metal behavior. this will provide a templ8 for building + complicated models that can capture even + elusive phenomena, s'as high-temperature superconductivity. and maybe even + than that.
“the universes and societies of electrons that we study aint 1-ly a subject of curiosity and intellectual satisfaction,” kim said. “they’re also a subject that makes a difference inna society. we can change society — revolutionize society — by cogging new materials, new kinds of states. the discovery of semiconductors led to the transistor. and we cannot imagine wha’ the realm ‘d be like tody if there were no transistors.”
the research was supported by the u.s. deptment of energy na simons foundation.
original content at: www.scidaily.com…