Scaling of the pinning force in MgB 2 superconductor

1. Vibrating Head Control Units(3) H , T and M. ZFC , FC Sample Holder Sample Zone The Sample (GPIB) Pickup Coils Special Program Magnetic Coils 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@kfupm.edu.sa Introduction GdG0 0 MRad. GdG1 10 MRad. GdG3 35MRad. GdG4 75MRad. GdG5 200MRad. GdG6 275MRad. Magnetic Measurements 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 Tc~94K 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 q~3 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,