CHARACTERISTIC CURVES OF M-H AND COEXISTENCE OF MAGNETISM WITH SUPERCONDUCTIVITY FOR HIGH T_c SUPERCONDUCTORS REBa_2Cu_3OT_(7-x)

Some high T_c superconductors REBa_2Cu_3O_(7-x)(RE=Sm,Eu,Gd,Dy,Ho,Er,Tm) with zero resist-ance temperatures were about 90K have been prepared.The effect of magnetic rare earth ions on the transi-tion temperatures is not very great,but their magnetic behaviours are different from each other.Themagnetization loops of these compounds have been measured at 77K.The coexistence of superconductivitywith magnetic ordering (COSM) found in the samples with RE=Gd,Dy,Ho,Er,Tm,indicates that thereare two possible ways of coexistence in the samples.These expertments show that the relation ofparamagnetism to the atomtc number of rare earth elements for these superconductors is similar to that ofrare earth ions in some paramagnetic salt crystals,which indicates that the magnetism of the samples origi-nates from the local magnetic moments of rare earth ions.In some samples there is antiferromagnetie orderingat low temperatures,and the effective Bohr magneton numbers are consistent with that of free rare earth ions.Some superconducting parameters including the critical current density are calculated according toGinzburg-Landau theory and the critical state model.     

JDM—14型VSM软件设计与实现

本文系统地介绍JDM—14型振动样品磁强计(VSM)的一种应用软件。通过本软件,可以自动求得规则样品的平均退磁因子,从而,把振动样品磁强计测量开路样品的磁参数自动转化为闭路样品(即物质)的磁特性参数。在已知样品质量和密度、或者样品体积的情况下,可以自动求出该物质的磁化强度、饱和磁化强度、磁化率、矫顽力、内凛矫顽力、剩磁以及磁化曲线、磁滞回线、退磁曲线和磁能积曲线等。