Study of the mixed state of La_{1.83}Sr_{0.17}CuO_{4} by means of muon-spin rotation and magnetization experiments in a low magnetic field

TL;DR

This study combines muon-spin rotation and magnetization experiments to investigate the vortex state and magnetic properties of La_{1.83}Sr_{0.17}CuO_{4} in a low magnetic field, revealing vortex pinning effects and temperature-dependent flux behavior.

Contribution

It provides new insights into vortex dynamics, pinning effects, and magnetic field distribution in a high-temperature cuprate superconductor using combined microscopic and macroscopic techniques.

Findings

Magnetization varies with cooling procedures.

Muon experiments show vortex pinning influences local magnetic fields.

Local flux density increases at low temperatures, indicating non-random vortex sampling.

Abstract

Muon-spin rotation (muSR) experiments are often used to study the magnetic field distribution in type-II superconductors in the vortex state. Based on the determination of the magnetic penetration depth it is frequently speculated---also controversially---about the order-parameter symmetry of the studied superconductors. This article reports on a combined muSR and magnetization study of the mixed state in the cuprate high-temperature superconductor La_{1.83}Sr_{0.17}CuO_{4} in a low magnetic field of 20 mT applied along the c axis of a single crystal. The macroscopic magnetization measurements reveal substantial differences for various cooling procedures. Yet, indicated changes in the vortex dynamics between different temperature regions as well as the results of the microscopic muSR experiments are virtually independent of the employed cooling cycles. Additionally, it is found that the mean magnetic flux density, locally probed by the muons, strongly increases at low temperatures. This can possibly be explained by a non-random sampling of the spatial field distribution of the vortex lattice in this cuprate superconductor caused by intensified vortex pinning.