N. Pillmayr

Electronic properties of the valence transition system YbIn1−xAgxCu4

Abstract Measurements of the electrical resistivity and the specific heat have been performed on YbIn1−xAgxCu4 intermetallics (0≤x≤1) to investigate the crossover from a first order valence transition in YbInCu4 to the dense Kondo lattice YbAgCu4.

Magnetism and specific heat of UIrGa5 and UPdGa5

Abstract Magnetization and specific heat measurements on UPdGa5 indicate antiferromagnetism at temperatures below 50 K. Neutron diffraction study shows, however, that the ordered magnetic moment of U should be very low (probably less than 0.5μB). UIrGa5 exhibits weak paramagnetism with susceptibility values around 1×10-8 m3/mol. The feeble magnetic properties of UTGa5 compounds are probably due to a strong hybridization of U 5f states with 4p states of Ga and d states of the transition metal.

Temperature and concentration dependence of the electrical resistivity in (RE, Y)Co2 (RE = rare earth element)

Abstract We study the influence of magnetic scattering processes on the temperature dependence of the electrical resistivity. This influence is caused by localized 4f-moments and spin-fluctuations. The pronounced minima in ϱ vs. T curves observed in the diluted RE-region are discussed in terms of enhanced spin-fluctuations and Kondo type scattering processes.

Specific heat measurements of (Ho, Y)Co2 and (Dy, Y)Co2

Abstract We report on concentration- and temperature-dependent specific heat measurements of (Dy x Y 1− x )Co 2 in the temperature range from 1.5 to 60 K in comparison with recent results of (Ho x Y 1− x )Co 2 . The magnetic contribution to the specific heat, C m , is analysed with regard to the appearance of spin-fluctuations and in terms of spin-glass phenomena. The loss of magnetic entropy in the dilute RE-concentration range indicates presumably an instability of the RE-moments.

Heat capacity of Sm2CuO4 and Sm1.85Ce0.15CuO4

Abstract We present specific heat measurements of Sm 2 CuO 4 and Sm 1.85 Ce 0.15 CuO 4 in external fields up to 11 T. Entropy considerations indicate that Ce is tetravalent in these systems.

Heavy fermion behaviour in Ce(CuxGa1−x)2

Abstract Measurements on transport properties, specific heat, susceptibility and of the magnetization of the pseudobinary Ce ( Cu x Ga 1− x ) 2 (0.5 ≤ x ≤ 1.0) system are presented. The substitution of Cu by Ga in CeCu 2 suppresses the long range magnetic order observed in CeCu 2 below 3.5 K, while Kondo interaction develops.

Influence of Cu and Ni substitution on the Kondo compound CeAl2

Abstract Measurements of the electrical resistivity, thermopower and of the specific heat of the pseudobinary series Ce(AlxM1−x)2 (M = Cu, Ni) show that due to this substitution the Kondo properties of CeAl2 diminish continuously. Additionally the substitution suppresses the long range magnetic order while spin freezing phenomena develop.

Heat capacity of (R1−xPrx)Ba2Cu3O7 (R=Y, Gd)

Abstract We present specific heat measurements of (R, Pr)Ba 2 Cu 3 O 7 (R=Y, Gd) in external fields up to 11 T. The results are analyzed in terms of crystalline electric field (CEF) effects and indicate that in these systems Pr appears to be trivalent rather than tetravalent.

Specific heat contributions to the heavy fermion compounds CeCu4M(M = Al, Ga)*

We present heat capacity measurements on polycrystalline CeCu 4 M (M = Al, Ga) compounds in the temperature range 50 mK ⩽ T ⩽ 55 K. They are characterized by extremely large values of the electronic contribution to the specific heat and pronounced Schottky anomalies caused by crystal field splitting.

A crossover from intermediate valence to integer valence in Yb(Cu,Al)5 compounds

Abstract Studies of transport properties, specific heat and susceptibility of various Yb(Cu x Al 1− x ) 5 compounds show that due to the Al/Cu exchange a stable 3+ state is revealed. In addition, evolution towards a pronounced Kondo behaviour is found.