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Title:Hall effect in the superconducting and normal states in detwinned and twinned single crystals of zinc-doped yttrium barium copper oxide
Author(s):Schegolev, Anton Igorevich
Doctoral Committee Chair(s):Ginsberg, D.M.
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Condensed Matter
Abstract:We have investigated the influence of zinc doping on the Hall effect in detwinned and twinned single crystals of $\rm YBa\sb2Cu\sb3O\sb{7-\delta}$. We observed the sign reversal of the Hall effect for crystals with superconducting transition temperature (T$\rm\sb{c}$) as low as 58.51K. Below the transition temperature, the Hall conductivity followed the C$\sb1$/H+C$\sb2$H law. According to the theory of the Hall effect in the mixed state$\sp{\lbrack 1\rbrack},$ the first term comes from the vortex motion's contribution, and the other term comes from the quasiparticles in the vortex cores.
We found that absolute value of the coefficient C$\sb1$ increased faster than (1-T/T$\rm\sb{c}$) with decreasing temperature. The C$\sb2$ coefficient was found to increase rapidly as T fell below T$\rm\sb{c}$ for crystals with T$\rm\sb{c}$ higher than 70K, supposedly because of the sharp increase in the quasiparticle mean free path.
We also found that the Hall effect is different in twinned and detwinned crystals; we found that the Hall coefficient in the normal state increased almost 20% after detwinning. The C$\sb1$ coefficient was found to be almost unaffected by twin boundaries while the C$\sb2$ coefficient increased a factor of two after detwinning. Such a behavior of C$\sb1$ suggests that the twin boundaries do not affect vortex motion once the field exceeds the depinning one. The substantial increase of C$\sb2$ and the Hall coefficient in the normal state by the detwinning points out that the disorder in the basal (or chain) plane is important for charge movement in the CuO$\sb2$ plane, and the disorder affects the process of charge transfer from chains to planes.
The depinning field was found to decrease during the removal of twin boundaries. This fact supports an idea that twin boundaries serve to pin vortices in $\rm YBa\sb2Cu\sb3O\sb{7-\delta}$.
The solubility limit of zinc in $\rm YBa\sb2Cu\sb3O\sb{7-\delta}$ single crystals was found to be slightly less than 4%.
This material is based upon work supported by National Science Foundation under Grant DMR 89-20538. ftn$\sp{\lbrack1\rbrack}$A. T. Dorsey, Phys. Rev. B 46, 8376 (1992); N. B. Kopnin, B. I. Ivlev, and V. A. Khalatsky, J. Low Temp. Phys. 90, 1 (1993); R. J. Troy and A. T. Dorsey, Phys. Rev. B 47, 2715 (1993); M. Feigel'man, V. Geshkenbein, A. Larkin, V. Vinokur, JETP Lett. 62, 834 (1995).
Issue Date:1996
Rights Information:Copyright 1996 Schegolev, Anton Igorevich
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9712428
OCLC Identifier:(UMI)AAI9712428

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