Pressure effect on the in-plane magnetic penetration depth in YBa_2Cu_4O_8

TL;DR

This study investigates how applying pressure affects the magnetic penetration depth in YBa_2Cu_4O_8, revealing significant changes linked to charge transfer and lattice coupling, which enhances understanding of high-temperature superconductor properties.

Contribution

It provides the first detailed measurement of pressure effects on the in-plane penetration depth in YBa_2Cu_4O_8, highlighting the role of charge transfer and lattice coupling.

Findings

Pressure causes a 44% increase in lambda_{ab}^{-2}(0) at 10.2 kbar.

Pressure influences the effective in-plane charge carrier mass.

Charge transfer from CuO chains to CuO_2 planes occurs under pressure.

Abstract

We report a study of the pressure effect (PE) on the in-plane magnetic field penetration depth lambda_{ab} in YBa_2Cu_4O_8 by means of Meissner fraction measurements. A pronounced PE on lambda_{ab}^{-2}(0) was observed with a maximum relative shift of \Delta\lambda^{-2}_{ab}/\lambda^{-2}_{ab}= 44(3)% at a pressure of 10.2 kbar. It arises from the pressure dependence of the effective in-plane charge carrier mass and pressure induced charge carrier transfer from the CuO chains to the superconducting CuO_2 planes. The present results imply that the charge carriers in YBa_2Cu_4O_8 are coupled to the lattice.