MAGNETIC-PROPERTIES AND LONG-RANGE MAGNETIC ORDER OF ER3+ IN ER2BA4CU7O14.92

The magnetic ordering of the Er ions in the high-temperature supercond uctor Er2Ba4Cu7O14.92 (T-c = 89 K) has been studied by low temperature heat capacity measurements and by neutron diffraction. A sharp peak i n the specific heat at T-N = 0.54 K can be described by an anisotropic two-dimensional (2D) Ising model. By neutron diffraction we observed a quasi three-dimensional (3D) antiferromagnetic order of the Er ions. The magnetic Er moments are oriented parallel to the b-axis. This wor k proves that Er-247 is the first compound in the 247 system showing a long-range magnetic ordering. (C) 1998 Elsevier Science B.V. All righ ts reserved.