Magnetic field dependence of the oxygen isotope effect on the magnetic penetration depth in hole-doped cuprate superconductors

TL;DR

This study investigates how magnetic fields influence the oxygen isotope effect on the magnetic penetration depth in hole-doped cuprate superconductors, revealing a significant field-dependent change linked to charge carrier mass.

Contribution

It demonstrates the magnetic field dependence of the oxygen isotope effect on the penetration depth and attributes it to variations in the in-plane charge carrier mass in cuprates.

Findings

Oxygen isotope effect on penetration depth decreases with magnetic field.

Stronger increase of b for O compared to O with field.

Field dependence explained by isotope variation in charge carrier mass.

Abstract

The magnetic field dependence of the oxygen-isotope (^{16}O/^{18}O) effect (OIE) on the in-plane magnetic field penetration depth \lambda_{ab} was studied in the hole-doped high-temperature cuprate superconductors YBa_2Cu_4O_8, Y_0.8Pr_0.2Ba_2Cu_3O_7-\delta, and Y_0.7Pr_0.3Ba_2Cu_3O_7-\delta. It was found that \lambda_ab for the ^{16}O substituted samples increases stronger with increasing magnetic field than for the ^{18}O ones. The OIE on \lambda_ab decreases by more than a factor of two with increasing magnetic field from \mu_0H=0.2 T to \mu_0H=0.6 T. This effect can be explained by the isotope dependence of the in-plane charge carrier mass m^\ast_{ab}.