Resistive Transitions of Ni-doped Ba sub 2 YCu sub 3 O sub 7 in High-Magnetic Fields.

Resistive transitions of single crystal Ba sub 2 YCu sub (3-z) Ni sub z O sub 7 were studied in magnetic fields up to 20 tesla. For dopant concentrations of x = 0.01 and x = 0.03, the transition temperature in zero field decreased from the undoped value of 88K to 82K and 76K respectively, while the transition width DELTAT (10%-90%) is still less than 1K. Moreover, Ni-doping has a dramatic effect on the resistive transition, tending to suppress the field dependent broadening.