Physical properties and crystal chemistry of Ce2Ga12Pt

Single crystals of the new ternary compound Ce2Ga12Pt were prepared by the self-flux technique. The crystal structure with the space group P4/nbm was established from single-crystal X-ray diffraction data and presents a derivative of the LaGa6Ni0.6 prototype. Magnetic susceptibility measurements show Curie-Weiss behaviour due to local Ce^3+ moments. At high temperatures, the magnetic anisotropy is dominated by the crystal-electric-field (CEF) effect with the easy axis along the crystallographic c direction. Ce2Ga12Pt undergoes two antiferromagnetic phase transitions at T_N,1 = 7.3K and T_N,2 = 5.5K and presents several metamagnetic transitions for the magnetic field along c. Specific-heat measurements prove the bulk nature of these magnetic transitions and reveal a doublet CEF ground state. The 4f contribution to the resistivity shows a broad maximum at T_max ~ 85K due to Kondo scattering off the CEF ground state and excited levels.Comment: 12 pages, accepted in J. Phys.: Condens. Matte

Structural investigations of CeIrIn5{_5} and CeCoIn5{_5} on macroscopic and atomic length scales

For any thorough investigation of complex physical properties, as encountered in strongly correlated electron systems, not only single crystals of highest quality but also a detailed knowledge of the structural properties of the material are pivotal prerequisites. Here, we combine physical and chemical investigations on the prototypical heavy fermion superconductors CeIrIn${_5}$ and CeCoIn${_5}$ on atomic and macroscopic length scale to gain insight into their precise structural properties. Our approach spans from enhanced resolution X-ray diffraction experiments to atomic resolution by means of Scanning Tunneling Microscopy (STM) and reveal a certain type of local features (coexistence of minority and majority structural patterns) in the tetragonal HoCoGa$_5$-type structure of both compounds.Comment: 8 pages, 5 figures, submitted to JPSJ (SCES 2013

Order and disorder in the modulated phase hp-Mg9Ge5.1

Single crystals of Mg9Ge5.1(2) were obtained at a pressure of 5 GPa in the temperature range 723 to 1273 K. The metastable high-pressure phase exhibits a crystal structure, which may be described as a host-guest variety of an UCl3-type framework. The atomic arrangement is characterized by a host crystal structure Mg9Ge3 with disordered germanium guests (≈2 Ge per formula unit) in the channels. The composite arrangement undergoes incommensurate modulation. Upon heating at ambient pressure, the phase transforms into the thermodynamically stable compounds Mg2Ge and Ge at 496(5) K. Measurements of the magnetic susceptibility indicate diamagnetic behavior between 75 and 350 K

Crystal Chemistry and Physics of UCd11

In the phase diagram U-Cd, only one compound has been identified so far─UCd11 (space group Pm3̅m). Since the discovery of this material, the physical properties of UCd11 have attracted a considerable amount of attention. In particular, its complex magnetic phase diagram─as a result of tuning with magnetic field or pressure─is not well-understood. From a chemical perspective, a range of lattice parameter values have been reported, suggesting a possibility of a considerable homogeneity range, i.e., UCd11-x. In this work, we perform a simultaneous study of crystallographic features coupled with measurements of physical properties. This work sheds light on the delicate relationship between the intrinsic crystal chemistry and magnetic properties of UCd11

Crystal Chemistry and Physics of UCd₁₁

In the phase diagram U-Cd, only one compound has been identified so farUCd11 (space group Pm3̅m). Since the discovery of this material, the physical properties of UCd11 have attracted a considerable amount of attention. In particular, its complex magnetic phase diagramas a result of tuning with magnetic field or pressureis not well-understood. From a chemical perspective, a range of lattice parameter values have been reported, suggesting a possibility of a considerable homogeneity range, i.e., UCd11–x. In this work, we perform a simultaneous study of crystallographic features coupled with measurements of physical properties. This work sheds light on the delicate relationship between the intrinsic crystal chemistry and magnetic properties of UCd11

BaGe₆ and BaGe_6‑x: Incommensurately Ordered Vacancies as Electron Traps

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe₆ (<i>P</i> = 15 GPa, <i>T</i> = 1073 K) and BaGe_6–<i>x</i> (<i>P</i> = 10 GPa, <i>T</i> = 1073 K) which are metastable at ambient conditions. In BaGe_6‑<i>x</i>, partial fragmentation of the BaGe₆ network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe_6–<i>x</i> is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe_6‑<i>x</i> for <i>x</i> = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity

BaGe₆ and BaGe_6‑x: Incommensurately Ordered Vacancies as Electron Traps

We report the high-pressure high-temperature synthesis of the germanium-based framework compounds BaGe₆ (<i>P</i> = 15 GPa, <i>T</i> = 1073 K) and BaGe_6–<i>x</i> (<i>P</i> = 10 GPa, <i>T</i> = 1073 K) which are metastable at ambient conditions. In BaGe_6‑<i>x</i>, partial fragmentation of the BaGe₆ network involves incommensurate modulations of both atomic positions and site occupancy. Bonding analysis in direct space reveals that the defect formation in BaGe_6–<i>x</i> is associated with the establishment of free electron pairs around the defects. In accordance with the electron precise composition of BaGe_6‑<i>x</i> for <i>x</i> = 0.5, physical measurements evidence semiconducting electron transport properties which are combined with low thermal conductivity