ac MH loop measurements on Mn doped YBa2Cu3O7-δ superconductors

Isothermal ac MH (magnetization-field) loops for varying field amplitudes were recorded at 77 K on YBa2(Cu1-xMnx)3O7-δ with x = 0, 0.010, 0.015, 0.020, 0.025, 0.035 and 0.050, YBa2(Cuo.o75Fe0.025)3O7-δ, YBa2(Cu0.075Ni0.025)3O7-δ and YBa2(Cu0.075Zn0.025)3O7-δ samples up to a maximum field amplitude of 80 Oe. Flat band susceptibility, ac losses and flux profiles were deduced from the ac MH loops. The undoped sample exhibited a minimum weak link ac loss and the 5.0% doped sample showed maximum weak link ac loss. Ni and Fe doped samples showed higher granular losses.Jcg estimated from the flux profiles decreases monotonically with increasing concentrations of Mn up to 2.5%.