On the interpretation of the equilibrium magnetization in the mixed state of high-Tc superconductors

TL;DR

This paper applies a new scaling method to analyze magnetization data of high-Tc superconductors, revealing different temperature dependencies and suggesting phase transitions, challenging existing theoretical models for these materials.

Contribution

It introduces a novel scaling procedure for analyzing equilibrium magnetization data in high-Tc superconductors, providing new insights into their critical fields and phase behavior.

Findings

Different temperature dependencies of critical fields and penetration depth.

Identification of a kink indicating a phase transition in the mixed state.

Existing models are inadequate for quantitative analysis of high-Tc superconductors.

Abstract

We apply a recently developed scaling procedure to the analysis of equilibrium magnetization M(H) data that were obtained for T-2212 and Bi-2212single crystals and were reported in the literature. The temperature dependencies of the upper critical field and the magnetic field penetration depth resulting from our analysis are distinctly different from those obtained in the original publications. We argue that theoretical models, which are usually employed for analyses of the equilibrium magnetization in the mixed state of type-II superconductors are not adequate for a quantitative description of high-Tc superconductors. In addition, we demonstrate that the scaled equilibrium magnetization M(H) curve for a Tl-2212 sample reveals a pronounced kink, suggesting a phase transition in the mixed state.