Pseudogap phase of cuprate superconductors confined by Fermi surface topology

The properties of cuprate high-temperature superconductors are largely shaped by competing phases whose nature is often a mystery. Chiefly among them is the pseudogap phase, which sets in at a doping p* that is material-dependent. What determines p* is currently an open question. Here we show that the pseudogap cannot open on an electron-like Fermi surface, and can only exist below the doping p (FS) at which the large Fermi surface goes from hole-like to electron-like, so that p* ≤ p (FS). We derive this result from high-magnetic-field transport measurements in La(1.6−x)Nd(0.4)Sr(x)CuO(4) under pressure, which reveal a large and unexpected shift of p* with pressure, driven by a corresponding shift in p (FS). This necessary condition for pseudogap formation, imposed by details of the Fermi surface, is a strong constraint for theories of the pseudogap phase. Our finding that p* can be tuned with a modest pressure opens a new route for experimental studies of the pseudogap.