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Title: Critical Currents of Ex-Situ YBa 2Cu 3O 7-δ Thin Films on Rolling Assisted Biaxially Textured Substrates: Thickness, Field, and Temperature Dependencies

Abstract

The critical current density J{sub c} flowing in thin YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films of various thicknesses d has been studied magnetometrically, both as a function of applied field H and temperature T, with a central objective to determine the dominant source of vortex pinning in these materials. The films, grown by a BaF{sub 2} ex situ process and deposited on buffered rolling assisted biaxially textured substrates ('RABiTS') substrates of Ni-5% W, have thicknesses d ranging from 28 nm to 1.5 {micro}m. Isothermal magnetization loops M(H;T) and remanent magnetization M{sub rem}(T) in H=0 were measured with H{parallel}c-axis (i.e., normal to film plane). The resulting J{sub c}(d) values (obtained from a modified critical state model) increase with thickness d, peak near d-120 nm, and thereafter decrease as the films get thicker. For a wide range of temperatures and intermediate fields, we find J{sub c} {infinity} H{sup -{alpha}} with {alpha}-(0.56-0.69) for all materials. This feature can be attributed to pinning by large random defects, which theoretically has power-law exponent {alpha} = 5/8. Calculated values for the size and density of defects are comparable with those observed by TEM in the films. As a function of temperature, we find J{sub c}(T,sf)-[1-(T/T{sub c}){supmore » 2}]{sup n} with n-1.2-1.4. This points to '{delta}T{sub c} pinning' (pinning that suppresses T{sub c} locally) in these YBCO materials.« less

Authors:
 [1];  [1];  [1];  [1];  [1];  [2]
  1. ORNL
  2. University of Wisconsin, Madison
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1003299
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 73; Journal Issue: 13; Journal ID: ISSN 1098--0121
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CRITICAL CURRENT; DEFECTS; MAGNETIZATION; ROLLING; SUBSTRATES; THICKNESS; THIN FILMS

Citation Formats

Ijaduola, Anota O, Thompson, James R, Feenstra, Roeland, Christen, David K, Gapud, Albert Agcaoili, and Song, X. Critical Currents of Ex-Situ YBa2Cu3O7-δ Thin Films on Rolling Assisted Biaxially Textured Substrates: Thickness, Field, and Temperature Dependencies. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.73.134502.
Ijaduola, Anota O, Thompson, James R, Feenstra, Roeland, Christen, David K, Gapud, Albert Agcaoili, & Song, X. Critical Currents of Ex-Situ YBa2Cu3O7-δ Thin Films on Rolling Assisted Biaxially Textured Substrates: Thickness, Field, and Temperature Dependencies. United States. https://doi.org/10.1103/PhysRevB.73.134502
Ijaduola, Anota O, Thompson, James R, Feenstra, Roeland, Christen, David K, Gapud, Albert Agcaoili, and Song, X. Sun . "Critical Currents of Ex-Situ YBa2Cu3O7-δ Thin Films on Rolling Assisted Biaxially Textured Substrates: Thickness, Field, and Temperature Dependencies". United States. https://doi.org/10.1103/PhysRevB.73.134502.
@article{osti_1003299,
title = {Critical Currents of Ex-Situ YBa2Cu3O7-δ Thin Films on Rolling Assisted Biaxially Textured Substrates: Thickness, Field, and Temperature Dependencies},
author = {Ijaduola, Anota O and Thompson, James R and Feenstra, Roeland and Christen, David K and Gapud, Albert Agcaoili and Song, X.},
abstractNote = {The critical current density J{sub c} flowing in thin YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) films of various thicknesses d has been studied magnetometrically, both as a function of applied field H and temperature T, with a central objective to determine the dominant source of vortex pinning in these materials. The films, grown by a BaF{sub 2} ex situ process and deposited on buffered rolling assisted biaxially textured substrates ('RABiTS') substrates of Ni-5% W, have thicknesses d ranging from 28 nm to 1.5 {micro}m. Isothermal magnetization loops M(H;T) and remanent magnetization M{sub rem}(T) in H=0 were measured with H{parallel}c-axis (i.e., normal to film plane). The resulting J{sub c}(d) values (obtained from a modified critical state model) increase with thickness d, peak near d-120 nm, and thereafter decrease as the films get thicker. For a wide range of temperatures and intermediate fields, we find J{sub c} {infinity} H{sup -{alpha}} with {alpha}-(0.56-0.69) for all materials. This feature can be attributed to pinning by large random defects, which theoretically has power-law exponent {alpha} = 5/8. Calculated values for the size and density of defects are comparable with those observed by TEM in the films. As a function of temperature, we find J{sub c}(T,sf)-[1-(T/T{sub c}){sup 2}]{sup n} with n-1.2-1.4. This points to '{delta}T{sub c} pinning' (pinning that suppresses T{sub c} locally) in these YBCO materials.},
doi = {10.1103/PhysRevB.73.134502},
url = {https://www.osti.gov/biblio/1003299}, journal = {Physical Review B},
issn = {1098--0121},
number = 13,
volume = 73,
place = {United States},
year = {2006},
month = {1}
}