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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 MgB 2 superconductor. Kh. A. Ziq*, Hala Hashem

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Presentation Transcript

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: [email protected]

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,


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