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We present band structure calculations of the non-magnetic compound LuRh2Si2 which serves as a reference for YbRh2Si2, a prototypical material for the investigation of quantum critical points. The relative z position of the Si atoms is found to have a strong impact on the band structure and the Fermi surface topology. We find the total energy to be minimized for z = 0.381 c whereas a comparison of predicted extremal orbits with Shubnikov-de Haas frequencies shows best agreement at the experimental value z = 0.379 c. We therefore recommend usage of z = 0.379 c for future electronic structure calculations of LuRh2Si2 and YbRh2Si2. [ABSTRACT FROM AUTHOR]

The intermetallic compound CeAgSb2 is an unusual example of a ferromagnetically ordered Kondo lattice system. Ferromagnetism sets in below the Curie temperature TC = 9.6 K at ambient pressure and zero fields. We have investigated the sensitivity of the ferromagnetic phase to hydrostatic pressure and a transverse magnetic tuning field using a series of resistivity and magnetization measurements. With pressure, TC is suppressed rapidly, and extrapolates to zero at 35 kbar. The ferromagnetism arising in CeAgSb2 is uniaxial, with the ordered moment aligning along the tetragonal c-axis. The application of an in-plane tuning field similarly suppresses TC, and drives the transition to zero temperature by 2.8 T. The character of the phase transition remains continuous on the approach to T = 0 K, and it is found that the quadratic A coefficient from the resistivity is strongly enhanced near the critical field. [ABSTRACT FROM AUTHOR]

We investigate the influence of small amounts of Ir and La substitution on the low-temperature thermal conductivity κ and thermopower S of YbRh2Si2. While the thermal conductivity is reduced in both cases due to the introduction of additional impurities, the effect on the thermopower is non-uniform: Ir substitution leads to a reduction of the absolute value of the thermopower. This is attributed largely to an enhanced disorder scattering. On the other hand, La substitution increases the absolute thermopower values. We discuss the possibility that this is due to band structure modifications upon doping into the Yb sublattice. [ABSTRACT FROM AUTHOR]

The intermetallic compound CeAgSb2 is an unusual example of a ferromagnetically ordered Kondo lattice system. Ferromagnetism sets in below the Curie temperature TC = 9.6 K at ambient pressure and zero fields. We have investigated the sensitivity of the ferromagnetic phase to hydrostatic pressure and a transverse magnetic tuning field using a series of resistivity and magnetization measurements. With pressure, TC is suppressed rapidly, and extrapolates to zero at 35 kbar. The ferromagnetism arising in CeAgSb2 is uniaxial, with the ordered moment aligning along the tetragonal c-axis. The application of an in-plane tuning field similarly suppresses TC, and drives the transition to zero temperature by 2.8 T. The character of the phase transition remains continuous on the approach to T = 0 K, and it is found that the quadratic A coefficient from the resistivity is strongly enhanced near the critical field. [ABSTRACT FROM AUTHOR]

We investigate the influence of small amounts of Ir and La substitution on the low-temperature thermal conductivity κ and thermopower S of YbRh2Si2. While the thermal conductivity is reduced in both cases due to the introduction of additional impurities, the effect on the thermopower is non-uniform: Ir substitution leads to a reduction of the absolute value of the thermopower. This is attributed largely to an enhanced disorder scattering. On the other hand, La substitution increases the absolute thermopower values. We discuss the possibility that this is due to band structure modifications upon doping into the Yb sublattice. [ABSTRACT FROM AUTHOR]