Magnetic studies of ultrathin slabs of copper-oxide materials reveal that at very low temperatures, the thinnest, isolated layers lose their long-range magnetic order and instead behave like a “quantum spin liquid” — a state of matter where the orientations of electron spins fluctuate wildly. This unexpected discovery may offer support for the idea that this novel condensed state of matter is a precursor to the emergence of high-temperature superconductivity — the ability to carry current with no resistance.