Relations entre les nouveaux supraconducteurs et l'antiferromagnétisme bi et tridimensionnel

With the classical superconductors there is nearly always an opposition with the local or itinerant magnetism. For the new superconductors there is a coexistence regime with the two-dimensional Cu antiferromagnetism of short coherence length, a fact wich can be related to a new attractive interaction due to magnetic fluctuations. However, the opposition between this new superconducting state and the three-dimensional antiferromagnetism is analyzed as a function of x proportional to the density of conduction electrons or holes, through the Ginzburg-Landau opposition term γM 2 ψ 2 between the two order parameters: if γ is beyond a critical value then there can be no overlap of the two transition temperatures T CM (x) and T CS (x), with nevertheless a common border observed for Nd 2-x CeCuO 4