High-pressure spin shifts in the pseudogap regime of superconducting YBa2Cu4O8 as revealed by 17O NMR

TL;DR

This study uses high-pressure NMR to explore how pressure affects the spin susceptibility and pseudogap in the superconductor YBa2Cu4O8, revealing pressure-induced changes in electronic properties.

Contribution

It introduces a new NMR anvil cell design and demonstrates how pressure modifies the spin susceptibility and pseudogap in a high-temperature superconductor.

Findings

Pressure increases spin shift at all temperatures.

Pseudogap feature diminishes at 63 kbar.

Pressure causes a proportional decrease in temperature-dependent component and an increase in temperature-independent component.

Abstract

A new NMR anvil cell design is used for measuring the influence of high pressure on the electronic properties of the high-temperature superconductor YBa$_2$Cu$_4$O$_8$ above the superconducting transition temperature $T_{\rm c}$. It is found that pressure increases the spin shift at all temperatures in such a way that the pseudo-gap feature has almost disappeared at 63 kbar. This change of the temperature dependent spin susceptibility can be explained by a pressure induced proportional decrease (factor of two) of a temperature dependent component, and an increase (factor of 9) of a temperature independent component, contrary to the effects of increasing doping. The results demonstrate that one can use anvil cell NMR to investigate the tuning of the electronic properties of correlated electronic materials with pressure.