Anisotropy of magnetic critical current density in HgBa₂CuO_4+δ

The anisotropy of magnetic critical current density in HgBa₂CuO_4+δ has been investigated. HgBa₂CuO_4+δ was synthesized from the mixed powders of HgO, BaO and CuO in evacuated quartz tube at 750°C for 1h. As-prepared HgBa₂CuO_4+δ was annealed in flowing argon at 300°C for 6h. Pulverized sample was aligned by a magnetic field of 8T in resin. The M-H loop measurements of magnetically aligned crystalline HgBa₂CuO_4+d were performed at 4.2K. The width of hysteresis loop, ΔM_ab in the a-b plane and ΔM_c along the c-axis, were calculated. The anisotropy of the width of hysteresis loop was observed, 1.6≤ΔM_cor ^ab/ΔM_cor ^c≤3.1 in magnetic field up to 9T. The critical current densities, J_c^ab in the a-b plane and J_c^c along the c-axis, were determined. The J_c^ab at 4.2K in 1T was found to be equal to 1.6×10⁶ A/cm².