High-temperature superconductivity in Nd$_{0.85}$Sr$_{0.15}$NiO$_2$ membranes under pressure

TL;DR

This study demonstrates that applying high pressure to Nd$_{0.85}$Sr$_{0.15}$NiO$_2$ membranes significantly increases their superconducting transition temperature, revealing a linear enhancement up to 90 GPa without saturation.

Contribution

The paper introduces a novel high-pressure technique using diamond anvil cells with freestanding nickelate membranes, enabling unprecedented exploration of pressure effects on superconductivity.

Findings

Superconducting transition temperature increases linearly with pressure at 0.65 K GPa$^{-1}$.

Superconductivity persists up to approximately 90 GPa, with no signs of saturation.

Pressure can be used to tune pairing strength in nickelates and potentially other 2D materials.

Abstract

Lattice compression has emerged as a fundamental tuning parameter for nickelate superconductivity. Pressure acts as a trigger to induce superconductivity in bulk Ruddlesden-Popper nickelates. For infinite-layer nickelate thin films, compressive epitaxial strain and rare-earth ion chemical pressure have been used to substantially enhance the superconducting transition temperature ($T_c$). Efforts to go further have been constrained by the limits of epitaxial stability or the challenges of measuring thin films in high-pressure environments. Here, we overcome this limitation by developing a technique to incorporate freestanding infinite-layer $\mathrm{Nd_{0.85}Sr_{0.15}NiO_2}$ membranes into a diamond anvil cell. Using this platform, we observe a strong increase in $T_c$ up to our highest measurement pressure of $\sim$90 GPa, where a superconducting downturn can be observed near liquid nitrogen temperatures. Strikingly, we find a simple linear enhancement of $T_c$ at a rate of 0.65 K GPa$^{-1}$, with no signs of saturation. This suggests that the pairing strength in infinite-layer nickelates can be raised to a surprisingly high scale, using an approach that can be broadly applied to many two-dimensional materials.