Pseudogap phase of cuprate superconductors confined by Fermi surface topology

TL;DR

This study reveals that the pseudogap phase in cuprate superconductors is constrained by Fermi surface topology, only forming below a specific doping level where the Fermi surface changes from hole-like to electron-like, and can be tuned by pressure.

Contribution

It demonstrates that the pseudogap cannot exist on an electron-like Fermi surface and establishes a direct link between pseudogap onset doping and Fermi surface topology, providing a new experimental control parameter.

Findings

Pseudogap exists only below the Fermi surface topology transition point.

Pressure shifts the pseudogap critical doping $p^*$ via Fermi surface changes.

Fermi surface topology imposes constraints on pseudogap formation theories.

Abstract

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 $p^*$ $\leq$ $p_{FS}$. 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.