Resistive properties of T1-ceramics in a pulsed magnetic field

In previous works we had reported about the revelation and investigation of dynamic magnetoresistance in ceramic high temperature (high-Tc) superconductors La1.85Sr0.15CuO4-x and YBa2Cu3O7-x (below LaSrCuO and YBaCuO). The appearance of this magnetoresistance under the influence of varying in time (pulsed) magnetic field B and at sufficiently low temperatures has been explained by the frustration of vortices from the pinning centers by varying magnetic field. As a result a motion of flux lines under the action of weak measuring current become possible, this motion is accompanied by viscous friction and give the rise to dynamic magnetoresistance. The measurements have been carried out on the sample of Tl-ceramics prepared in three-stage heat treatment of Ba(NO2)3. (orig./BHO)