Field Induced Reduction of the Low Temperature Superfluid Density in YBa2Cu3O6.95

TL;DR

This study uses a high magnetic field muon spin rotation spectrometer to investigate how strong magnetic fields affect the low-temperature superfluid density in YBa2Cu3O6.95, revealing a field-induced suppression of temperature dependence.

Contribution

It presents the first observation of field-induced suppression of the linear temperature dependence of the superfluid density in a high-temperature superconductor.

Findings

Low magnetic fields show linear T dependence of penetration depth.

High magnetic fields suppress the temperature dependence at low T.

Results suggest a field-induced modification of the low-energy excitation spectrum.

Abstract

A novel high magnetic field (8 T) spectrometer for muon spin rotation has been used to measure the temperature dependence of the in-plane magnetic penetration depth in YBa2Cu3O6.95. At low H and low T, the penetration depth exhibits the characteristic linear T dependence associated with the energy gap of a d_x^2-y^2-wave superconductor. However, at higher fields the penetration depth is essentially temperature independent at low T. We discuss possible interpretations of this surprising new feature in the low-energy excitation spectrum.