Structural and magnetic properties of the Kagome antiferromagnet YbBaCo4O7

Journal article

The mixed-valent compound YbBaCo4O7 is built up of Kagomé sheets of CoO4 tetrahedra, linked in the third dimension by a triangular layer of CoO4 tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr9xGa12-9xO 19 (SCGO). We have undertaken a study of the structural and magnetic properties of this compound using combined high-resolution powder neutron and synchrotron X-ray diffraction. YbBaCo4O7 undergoes a first-order trigonal→orthorhombic phase transition at 175 K. We show that this transition occurs as a response to a markedly underbonded Ba2+ site in the high-temperature phase and does not appear to involve charge ordering of Co2+/Co3+ ions in the tetrahedra. The symmetry lowering relieves the geometric frustration of the structure, and a long-range-ordered 3-D antiferromagnetic state develops below 80 K.

Authors: Huq, A; Mitchell, J; Zheng, H; Chapon, L; Radaelli, P

• Publication status: Published
• Journal: JOURNAL OF SOLID STATE CHEMISTRY
• Volume: 179
• Issue: 4
• Pages: 1136-1145
• Publication date: 2006-04-01
• DOI: 10.1016/j.jssc.2006.01.010
• EISSN: 1095-726X
• ISSN: 0022-4596
• Language: English
• Keywords: neutron diffraction; cobaltite; charge-order; mixed-valent; geometric frustration; Kagome