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http://hdl.handle.net/123456789/89
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| Title: | THE STUDY OF UPPER CRITICAL FIELD CALCULETION OF SUPERCONDUCTING MAGNESIUM DIBORAIDE |
| Authors: | Habte, Dulla |
| Date Added: | 6-Sep-2007 |
| Abstract: | Magnesium diboride(MgB2) has joined the class of high Tc superconductors following the
discovery of superconductivity in this compound in 2001 below Tc 40k. A large part of
the excitement is due to the vast amount of unusual properties originating from the involvement
in superconductivity of two sets of bands that are of a very different nature. Because of
the different dimensionality of the two sets of bands,this”two band superconductivity” leads
to a complex behavior of the anisotropic superconducting state properties as a function of
magnetic field and temperature. The purpose of this thesis is to study the upper critical field
(Hc2) of two-band s-wave superconducting magnesium diboride(MgB2) in the vicinity of Tc
using a two-band Ginzburg-Landau(GL) theory. The analytical formula of Hc2(T) involving
anisotropy of order parameter and anisotropy of effective-mass are found. The parameters
of the upper critical field in ab-plane(Hab
c2 ) and c-axis (Hc
c2) can be found by fitting to the experimental
data. In addition to this we have considered the linearized two band Eilenberger
equations to calculate the upper critical field of superconducting magnesium diboride. Finally
by taking the ratio of the upper critical field ( the fields in ab-plane and c-axis) we tried
to show the anisotropy property of superconducting magnesium diboride. We observe that
the ratio of the two fields strongly depends on temperature. So, this ratio of upper critical
field is in the range of experimental result and temperature dependent.
Key words: S-wave superconductor,anisotropy two-band superconductors,Ginzburg-Landau
approach,Eilenberger equations,Magnesium diboride. |
| Description: | A THESIS PRESENTED TO
THE SCHOOL OF GRADUATE STUDIES
ADDIS ABABA UNIVERSITY
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF
MASTER OF SCIENCE in PHYSICS |
| URI: | http://hdl.handle.net/123456789/89 |
| Appears in: | Thesis - Physics
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