Evidence for 2D-3D magnetic ordering of Gd in high-Tc-relatedCaGdCuO3Cl andCa4R2Cu3O8Cl4(R=Gd,Sm)

Abstract

The magnetic susceptibilities of two high- T c -related semiconducting copper oxychlorides CaGdCuO 3 Cl and Ca 4 Gd 2 Cu 3 O 8 Cl 4 have been measured between 1.8 and 300 K. While magnetic ordering of Gd moments in all other high- T c -related compounds seems to be three-dimensional (3D), we see evidence for 2D-3D ordering of Gd moments in these copper oxychlorides. These ordering processes have been discussed on the basis of large anisotropy of the structure of these compounds compared to one of their parent structures Gd 2 CuO 4 . We have also carried out magnetic-susceptibility measurement on Ca 4 Sm 2 Cu 3 O 8 Cl 4 , where there is no indication for Sm ordering down to 1.8 K. © 1996 The American Physical Society.