A caged compound CeOs2 Al10, crystallizing in the orthorhombic YbFe2 Al10 -type structure, undergoes a mysterious phase transition at T0 =29 K. We report the results of electron diffraction, magnetization, and magnetoresistance for single crystals. Superlattice reflections characterized by a wave vector q= (0,-2/3,2/3) observed at 15 K indicate a structural modification in the ordered state. Activation-type behavior of the electrical resistivity along the three principal axes below 50 K suggests gap opening in the conduction band. The magnetic susceptibility χ=M/B is highly anisotropic, χa > χc > χb, all of which sharply decrease on cooling below T0. Furthermore, a metamagnetic anomaly in the magnetization and a step in the magnetoresistance occur at B=6-8 T only when the magnetic field is applied parallel to the orthorhombic c axis. However, T0 hardly changes under magnetic fields up to 14 T, irrespective of the field direction. By using these data, we present a B-T phase diagram and discuss several scenarios for the mysterious transition.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2010 Jun 2|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics