LOw-temperature ferromagnetism in La4Ba2Cu2O10

• Published in: Nature (London) Vol. 345; no. 6278; pp. 788 - 789
• Main Authors: MIZUMO, F, MASUDA, H, HIRABAYASHI, I, TANAKA, S, HASEGAWA, M, MIZUTANI, U
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 28-06-1990
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Superconductivity; Measure theory; Ferromagnetism; Superconductivity
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/345788a0

The origin of the ferromagnetic-like behavior previously observed near 5 K in impure samples of LaBa2Cu3O7 prepared under a reduced oxygen atmosphere is identified as the presence of an impurity phase, La4Ba2Cu2O10 (the 422 phase). The 422 phase contains square planar CuO4 units, with each of these units lying perpendicular to those around it. Magnetization measurements indicate an effective magnetic moment of 1.66 mu(B) per copper ion, with a saturation magnetic moment of 0.95 mu(B) per Cu. These results suggest that the compound is a localized ferromagnet in which the copper ions are magnetically ordered. It is suggested that the ferromagnetic coupling may originate in the orthogonality of the CuO4 units. The 422 phase could provide flux-pinning centers in bulk superconducting LaBa2Cu3O(7-y). (C.D.)