The specific heat of Pr1−xLaxOs4Sb12 alloys was measured in fields to 14 T. CEF energies remain approximately constant across this system. The field-induced AFQ order is suppressed by the alloying and is not observed for x=0.2 above 0.4 K. ©2006 American Institute of Physics

We have measured the specific heat (Cmag) of single crystals of the quasi-one-dimensional (Q1D) S=1 bond-alternating antiferromagnet Ni(C9H24N4)NO2(ClO4), alias NTENP, down to 250 mK. in a magnetic field up to 20 T applied along the chain. NTENP has a singlet ground state with an energy gap, which closes at a critical magnetic field Hc. We have found that Cmag/T is constant above Hc over a temperature range above that of the long-range ordered state

Cs2CuBr4 is one of the best candidates for the spin-1/2 Heisenberg antiferromagnet on the triangular lattice. To date, it is the only spin-1/2 material in which a magnetization plateau has been observed at 1/3 of the saturation magnetization — the hallmark of the triangular-lattice Heisenberg antiferromagnet. We have made a detailed determination of the magnetic phase diagram of Cs2CuBr4 in magnetic fields up to 18 T, using specific-heat and magnetocaloric-effect

Magnetic field–temperature phase diagram of PrOs4Sb12 was studied by specific heat measurements. Above 13 T we observe a new anomaly that we associate with a Schottky maximum corresponding to a two level system with identical degeneracies. The temperature of this maximum increases with the field up to the highest field studied of 32 T. This new anomaly has strong implications on a possible crystal field configuration of Pr and the origin of the

The specific heat of polycrystalline Ce0.6La0.4Pb3 has been measured in magnetic fields ranging from 0 to 14 T. After subtraction of a lattice contribution, the specific heat between 1 K and 10 K is well described by the S=(1/2) single-impurity Kondo model with just one adjustable parameter: the zero-field Kondo temperature. In particular, the variation in the temperature and the height of the peak in C vs T is captured with good accuracy. This fit

Specific-heat experiments on single crystals of the S=1 quasi-one-dimensional bond-alternating antiferromagnet Ni(C9H24N4)(NO2)ClO4 (NTENP) have been performed in magnetic fields applied both parallel and perpendicular to the spin chains. We have found for the parallel field configuration that the magnetic specific heat (Cmag) is proportional to temperature (T) above a critical field Hc, at which the energy gap vanishes, in a temperature region above

We review the results of specific-heat experiments on the S = 1 quasi-one-dimensional (quasi-1D) bond-alternating antiferromagnet Ni(C9H24N4)(NO2)ClO4, alias NTENP. At low temperatures above the transition temperature of a field-induced long-range order, the magnetic specific heat (Cmag) of this compound becomes proportional to temperature (T), when a magnetic field along the spin chains exceeds the critical field Hc at which the energy gap vanishes.

The specific heat and magnetocaloric effect are used to probe the field-induced up-up-down (UUD) phase of Cs2CuBr4, a quasi-two-dimensional spin-(1/2) triangular antiferromagnet with near-maximal frustration. The transitions between the commensurate UUD phase and the incommensurate phases adjacent to it are clearly first order, at least at low temperatures. The shape of the magnetic phase diagram shows that the UUD phase is stabilized by quantum

Electrical resistivity measurements of nonmagnetic single-crystalline Ce1−xLaxOs4Sb12 alloys, x=0.02 and 0.1, are reported for temperatures down to 20 mK and magnetic fields up to 18 T. At the lowest temperatures, the resistivity of Ce0.98La0.02Os4Sb12 has a Fermi-liquid-like temperature variation rho=rho0+AT^2 but with negative A in small fields. The resistivity has an unusually strong magnetic field dependence for a paramagnetic metal. The 20

Resistivity measurements were performed on Pr1-xLaxOs4Sb12 single crystals at temperatures down to 20 mK and in fields up to 18 T. The results for dilute-Pr samples x=0.3 and 0.67 are consistent with model calculations performed assuming a singlet crystalline-electric-field CEF ground state. The residual resistivity of these crystals features a smeared step centered around 9 T, the predicted crossing field for the lowest CEF levels. The CEF contribution