Magnetic and magnetotransport properties of polycrystalline YBA(2)Cu(3)O(7)
Abstract
The purpose of the present study was to investigate magnetic and magnetotransport behaviors of polycrystalline YBa2Cu3O7 (poly-YBCO). Magnetic phase diagrams for poly-YBCO samples with a range of density and grain size, were constructed using a combination of results from bulk magnetic and magnetotransport measurements. Critical scaling of the electric field as a function of current density, E(J), curves suggests the possibility of a phase transition into a state characterized by zero linear-resistance. The magnetization as a function of external applied magnetic field M(Hext ) of polycrystalline poly-YBCO, was studied by correlation of bulk magnetic measurement, and local measurement using micron-size Hall sensor arrays. The magnetization of poly-YBCO exhibits behavior that is more consistent with the geometrical barrier model of than that of either the Bean-Livingston surface barrier model or the Bean critical state strong-pinning model. The hysteretic field dependence of the critical current density Jc, can be explained based on the penetration of magnetic flux between, and into, the individual grains of the polycrystalline material.
Degree
Ph.D.
Advisors
McElfresh, Purdue University.
Subject Area
Condensation
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