Magneto‐transport properties of polycrystalline YBa₂(Cu_1‐xM_x)₃O_7‐δ (M = B and Mn)

Abstract

The magnetic and transport properties of polycrystalline YBa 2 (Cu 1-x M x ) 3 O 7-δ (M = B and Mn) superconductor was investigated. Samples of YBa 2 (Cu 1-x B x ) 3 O 7-δ doped with several concentrations of boron B (x = 0.05 and 0.1) were investigated using magnetization measurements. A YBa 2 (Cu 1-x Mn x ) 3 O 7-δ sample doped with Mn with concentration of x = 0.02 was investigated using current-voltage (I-V) measurements. Our results on the YBa 2 (Cu 1-x B x ) 3 O 7-δ samples reveal a considerable increase in the hysterisis width of the magnetization, M versus the applied magnetic field H with increasing boron concentration. The lower critical field was also found to be enhanced by boron doping. The critical current density, J c was found to be significantly enhanced in the Mn-doped sample. The enhancement of J c was found to be more significant at the lower temperatures for all applied magnetic fields used (0 Oe, 300 Oe, and 500 Oe). Thus, chemical doping is suggested to enhance the vortex pinning forces in the YBCO samples. From the resistivity (R-T) measurements, chemical doping of the samples was found to have no significant effect on the critical temperature, T c .