Abstract
We report the temperature and field dependence of the Meissner flux expulsion of sintered pellets of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y} with 0{<=}x{<=}0.08. In all samples the flux expulsion remains incomplete (-4 {pi}{chi}{approx}1/3) down to fields, which are much smaller than H{sub c1}, but for H{<=}2 Oe they all finally exhibit a full Meissner effect and are therefore fully superconducting. The expulsion in 2 Oe decreases to near 30% by aging of the grain boundaries and goes back to near 100% after their reoxidation, all at a fixed and sharp T{sub c} of 93 K. The data are interpreted in terms of equilibrium properties of granular high temperature superconductors on the basis of an analysis, which is described in detail in the following paper. An average cross-section of the superconducting `grains` in the CuO planes of 4 {mu}m{sup 2} is extracted from the temperature and field dependence of the spontaneous flux expulsion. These `grains` lie within the much larger crystallographic grains and are bordered by planar defects. Superconducting loops around these planar defects are responsible for the final flux expulsion in H < 2 Oe. An intrinsic transition width {Delta}T{sub c} can also be extracted from the data. One
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Citation Formats
Ruppel, S, Michels, G, Geus, H, Kalenborn, J, Schlabitz, W, and Wohlleben, D.
The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1. The Meissner effect of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y}.
Germany: N. p.,
1990.
Web.
Ruppel, S, Michels, G, Geus, H, Kalenborn, J, Schlabitz, W, & Wohlleben, D.
The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1. The Meissner effect of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y}.
Germany.
Ruppel, S, Michels, G, Geus, H, Kalenborn, J, Schlabitz, W, and Wohlleben, D.
1990.
"The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1. The Meissner effect of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y}."
Germany.
@misc{etde_10131488,
title = {The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1. The Meissner effect of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y}}
author = {Ruppel, S, Michels, G, Geus, H, Kalenborn, J, Schlabitz, W, and Wohlleben, D}
abstractNote = {We report the temperature and field dependence of the Meissner flux expulsion of sintered pellets of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y} with 0{<=}x{<=}0.08. In all samples the flux expulsion remains incomplete (-4 {pi}{chi}{approx}1/3) down to fields, which are much smaller than H{sub c1}, but for H{<=}2 Oe they all finally exhibit a full Meissner effect and are therefore fully superconducting. The expulsion in 2 Oe decreases to near 30% by aging of the grain boundaries and goes back to near 100% after their reoxidation, all at a fixed and sharp T{sub c} of 93 K. The data are interpreted in terms of equilibrium properties of granular high temperature superconductors on the basis of an analysis, which is described in detail in the following paper. An average cross-section of the superconducting `grains` in the CuO planes of 4 {mu}m{sup 2} is extracted from the temperature and field dependence of the spontaneous flux expulsion. These `grains` lie within the much larger crystallographic grains and are bordered by planar defects. Superconducting loops around these planar defects are responsible for the final flux expulsion in H < 2 Oe. An intrinsic transition width {Delta}T{sub c} can also be extracted from the data. One finds {Delta}T{sub c}{<=}1 K in the orthorhombic phase (x {<=} 0.02), while in the quasitetragonal phase, {Delta}T{sub c} increases from 1 to 16 K for 0.02 < x {<=} 0.08. (orig.)}
place = {Germany}
year = {1990}
month = {Apr}
}
title = {The equilibrium magnetization of granular high temperature superconductors in low fields. Pt. 1. The Meissner effect of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y}}
author = {Ruppel, S, Michels, G, Geus, H, Kalenborn, J, Schlabitz, W, and Wohlleben, D}
abstractNote = {We report the temperature and field dependence of the Meissner flux expulsion of sintered pellets of YBa{sub 2}(Cu{sub 1-x}Fe{sub x}){sub 3}O{sub 7-y} with 0{<=}x{<=}0.08. In all samples the flux expulsion remains incomplete (-4 {pi}{chi}{approx}1/3) down to fields, which are much smaller than H{sub c1}, but for H{<=}2 Oe they all finally exhibit a full Meissner effect and are therefore fully superconducting. The expulsion in 2 Oe decreases to near 30% by aging of the grain boundaries and goes back to near 100% after their reoxidation, all at a fixed and sharp T{sub c} of 93 K. The data are interpreted in terms of equilibrium properties of granular high temperature superconductors on the basis of an analysis, which is described in detail in the following paper. An average cross-section of the superconducting `grains` in the CuO planes of 4 {mu}m{sup 2} is extracted from the temperature and field dependence of the spontaneous flux expulsion. These `grains` lie within the much larger crystallographic grains and are bordered by planar defects. Superconducting loops around these planar defects are responsible for the final flux expulsion in H < 2 Oe. An intrinsic transition width {Delta}T{sub c} can also be extracted from the data. One finds {Delta}T{sub c}{<=}1 K in the orthorhombic phase (x {<=} 0.02), while in the quasitetragonal phase, {Delta}T{sub c} increases from 1 to 16 K for 0.02 < x {<=} 0.08. (orig.)}
place = {Germany}
year = {1990}
month = {Apr}
}