Instabilities of the Vortex Lattice and the Peak Effect in Single Crystal YBa2Cu4O8

Mehmet Egilmez,Isaac Isaac,Kim H Chow,Jan Jung,Zbigniew Bukowski,Janusz Karpinski,Ali S Alnaser

doi:10.3390/condmat4030074

Mehmet Egilmez, Isaac Isaac + Show 5 more

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https://doi.org/10.3390/condmat4030074

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Abstract

We report on the measurements of the remnant magnetization, and hence critical current, in a single crystal of YBa2Cu4O8. A peak in the temperature dependence of the critical current is observed when the external magnetic field is tilted away from the a–b planes. The observed behavior is attributed to a thermally activated instability-driven vortex-lattice splitting or vortex chain formation. The nature of the peak and the possibility of a thermally-activated dimensional crossover have been discussed.

Highlights

The properties of vortex-lattice tilted with respect to the CuO2 planes of a layered superconductor have been the subject of intense experimental and theoretical investigations [1,2].By considering the layered nature of cuprate superconductors, Tachiki and Takahashi [3] were the first to suggest that the modulation of the order parameter perpendicular to the CuO2 layers can trap the vortices between the layers
Experimental studies of such a temperature-induced instability of the vortex lattice are scarce. In this transformation results in a peak in the temperature-dependent remnant magnetization that is report, we present the experimental observation of a thermally-activated transformation of the vortex proportional to the critical current density
Its structure is composed of stacked composed of stacked CuO2 plane bi-layers with the unit cell

Summary

Introduction

The properties of vortex-lattice tilted with respect to the CuO2 planes (the a–b planes) of a layered superconductor have been the subject of intense experimental and theoretical investigations [1,2].By considering the layered nature of cuprate superconductors, Tachiki and Takahashi [3] were the first to suggest that the modulation of the order parameter perpendicular to the CuO2 layers can trap the vortices between the layers. The subsequent theoretical works by Feinberg [4] Blatter et al [5], Ivlev et al [6], Koshelev [7,8] and Bulaevskii [9] have pointed out that pinning of vortices between the layers occurs only when the angle θ between the CuO2 planes and the direction of the external magnetic field H does not exceed a certain critical angle θc. At small angles of tilt of H with respect to the a–b planes, the vortex lines are “locked” along the layers and the z-component of the magnetic field (Hz ) along the c-axis is screened. Hz occurs through the formation of kinks on the vortex lines The presence of such intrinsic pinning by the layered structure was confirmed by the measurements of the angular dependence of the resistivity in a magnetic field at a temperature close to Tc in a single crystal of YBa2 Cu3 O7−δ [10]

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