Scaling of the pinning force in MgB2

1
Scaling of the pinning force in
MgB2 superconductor
Kh. A. Ziq, Hala Hashem Department of Physics,
King Fahd University of Petroleum and
Minerals Dhahran Saudi Arabia 31261
Contact kaziq_at_kfupm.edu.sa
Introduction
Magnetic Measurements
GdG0 0 MRad. GdG1 10 MRad. GdG3
35MRad. GdG4 75MRad. GdG5 200MRad. GdG6
275MRad.
Abstract Hysteresis loops measurements have been
performed on MgB2 superconductor. The
thermodynamic critical field (Hc) has been used
to search for universal behavior in the critical
field and pinning force in the vortex state. This
scaling behavior has been found to be having
advantage over the traditional scaling behavior
commonly applied to wide class of superconducting
materials.
Samples Solid State Reaction Tc94K
GdBa2Cu3O7 Co60 gamma source Doses 7MRad/h
Objectives Gamma Ray effects on Magnetic and
superconducting properties of GdBa2Cu3O7
Mr Jc Pf Ms
The Co-60 source emits two g photons (1.33 and
1.17 MeV) per disintegration and its activity was
244 kGy (9.03 PBq). Max T at the surface of the
samples during irradiation 41 C.
Magnetization Results
Hysteresis loops
Low and high fields effects.
High T and low H
High field

• Saturated magnetization at low Temperatures.
• 2. Almost linear above 20K

• Irradiated samples
• The effect is clearly seen close to Tc and at low
  and high fields.
• At low fields The effect is due to increase in
  the density of defects at the grain boundaries.
• At high field The effect is due to the density
  of defects inside the grains.

Defects radius 1/(H)0.5
Remanent Magnetization and Pinning Forces
Susceptibility

• Pinning forces
• Pf increases with gamma dose.
• The peak position shifts to higher H-values with
  increasing radiation dose

• Mr vs T
• Mr is a measure of the critical current density
  at zero magnetic field.
• The initial increase in Mr with gamma-dose.
• The initial drop in Mr is logarithmic with
  temperature, followed by less gradual decrease.
• may be due to different pinning mechanism

q3 K
Adam Bridge
Conclusion
An increase in pinning at low Gamma radiation
levels At high fields Defects radius 1/sqrt(H).
A slight decrease in Ordering temperature with
Gamma doses. Little effects on Ms. Gd123 is
more resistive to Gamma radiation than Y123,