• Valldor, M.
• Schmidt, M.
• Pi, T.-W.
• Meven, M.
• Schweika, W.
• Hu, Z.
• Leo, N. R.
• Meier, D.
• Fiebig, Manfred
• Reim, J. D.
• Kuo, C.-Y.
• Rosén, E.

Abstract

<jats:p>Centimetre-sized single crystals of high-quality CaBaCo<jats:sub>2</jats:sub>Fe<jats:sub>2</jats:sub>O<jats:sub>7</jats:sub>were synthesized by the optical floating zone technique. The metal-to-metal stoichiometry and oxygen content were confirmed by spectroscopy and thermal reduction experiments. The hexagonal symmetry<jats:italic>P</jats:italic>6<jats:sub>3</jats:sub><jats:italic>mc</jats:italic>(No. 186) well describes the powder X-ray and neutron diffraction as well as single-crystal neutron diffraction at all measured temperatures. This symmetry is also consistent with optical second harmonic generation data obtained between 10 and 295 K. However, a satisfactory structure description from single-crystal neutron diffraction data needs an oxygen split position. Specific heat, magnetic susceptibility and powder neutron diffraction data indicate a magnetic phase transition at<jats:italic>T</jats:italic><jats:sub>N</jats:sub>= 159 K to an antiferromagnetic ground state, but with a persisting hexagonal symmetry and intrinsic geometric frustration.</jats:p>

Topics

• impedance spectroscopy
• single crystal
• phase
• experiment
• Oxygen
• phase transition
• neutron diffraction
• susceptibility
• oxygen content
• specific heat