A layered cake where each tier conducts electricity differently: that's the structure of the crystal La3Ni2O7, a compound of nickel, lanthanum, and oxygen. Current flows differently along the layers than across them. Researchers measured the resistance of this material with high precision by squeezing it with diamond anvils to pressures of tens of thousands of atmospheres.
As pressure increases, two charge density waves appear in the crystal — regions where electrons organize into ordered structures, like ripples on water. One of these waves is sensitive to compression and quickly disappears; the other holds on longer. While the waves exist, resistance is high, and current flows especially reluctantly across the layers — the difference in properties along different directions (anisotropy) becomes stronger.
When both waves are fully suppressed, resistance drops to zero — superconductivity sets in. But the most interesting part happens just above the critical temperature: the material becomes a "strange metal." In this state, scattering of charge carriers reaches the Planckian limit — a fundamental bound tied to the quantum nature of thermal motion. Electrons collide as often as physically possible in our world.
The Planckian scattering limit means that the time between electron collisions is determined only by temperature and Planck's constant, like a built-in metronome that cannot be fooled.
In Peter Watts's novel Blindsight, alien creatures use superconducting structures for instantaneous signal transmission — ideas like this are inspired by exactly such materials.