Giant Isotropic Nernst Effect in an Anisotropic Kondo Semimetal.

The "failed Kondo insulator" CeNiSn has long been suspected to be a nodal metal, with a node in the hybridization matrix elements. Here we carry out a series of Nernst effect experiments to delineate whether the severely anisotropic magnetotransport coefficients do indeed derive from a nodal metal or can simply be explained by a highly anisotropic Fermi surface. Our experiments reveal that despite an almost twentyfold anisotropy in the Hall conductivity, the large Nernst signal is isotropic.

Homo- and heterovalent substitutions in the new clathrates I Si30P16Te(8-x)Se(x) and Si(30+x)P(16-x)Te(8-x)Br(x): synthesis, crystal structure, and thermoelectric properties.

The new cationic clathrates I Si(30)P(16)Te(8-x)Se(x) and Si(30+x)P(16-x)Te(8-x)Br(x) were synthesized by the standard ampule technique. The Si(30)P(16)Te(8-x)Se(x) (x = 0-2.3) clathrates crystallize in the cubic space group Pm3̅n with the unit cell parameter a ranging from 9.

Single-Ion Kondo scaling of the coherent Fermi liquid regime in Ce(1-x)La(x)Ni2Ge2.

Thermodynamic and transport properties of the La-diluted Kondo lattice CeNi(2)Ge(2) were studied in a wide temperature range. The Ce-rich alloys Ce(1-x)La(x)Ni(2)Ge(2) were found to exhibit distinct features of the coherent heavy Fermi liquid. At intermediate compositions (0.

Thermoelectric properties of lead chalcogenide core-shell nanostructures.

We present the full thermoelectric characterization of nanostructured bulk PbTe and PbTe-PbSe samples fabricated from colloidal core-shell nanoparticles followed by spark plasma sintering. An unusually large thermopower is found in both materials, and the possibility of energy filtering as opposed to grain boundary scattering as an explanation is discussed. A decreased Debye temperature and an increased molar specific heat are in accordance with recent predictions for nanostructured materials.

Facile general route toward tunable Magnéli nanostructures and their use as thermoelectric metal oxide/carbon nanocomposites.

Engineering nanoscale interfaces is a requisite for harnessing electrical and thermal transports within nanostructured materials, especially those destined for thermoelectric applications requiring an unusual combination of low thermal conductivity and electrical resistivity. Nanocomposites open up possibilities in this area, but are still bound to a very narrow range of materials. Here, we report a new approach combining the sol-gel process toward hybrid materials with spark plasma sintering (SPS) to yield functional nanocomposites based on substoichiometric titanium oxides Ti(n)O(2n-1), so-called Magnéli phases.

Discontinuous Hall coefficient at the quantum critical point in YbRh₂Si₂.

YbRh2Si2 is a model system for quantum criticality. In particular, Hall effect measurements helped identify the unconventional nature of its quantum critical point. Here, we present a high-resolution study of the Hall effect and magnetoresistivity on samples of different quality.

Atomic interactions in the p-type clathrate I Ba8Au5.3Ge40.7.

Single crystals of Ba(8)Au(5.3)Ge(40.7) [space group Pm(3)n (No.

Fermi-surface collapse and dynamical scaling near a quantum-critical point.

Quantum criticality arises when a macroscopic phase of matter undergoes a continuous transformation at zero temperature. While the collective fluctuations at quantum-critical points are being increasingly recognized as playing an important role in a wide range of quantum materials, the nature of the underlying quantum-critical excitations remains poorly understood. Here we report in-depth measurements of the Hall effect in the heavy-fermion metal YbRh(2)Si(2), a prototypical system for quantum criticality.

Crystal chemistry and physical properties of the nonmagnetic Kondo compound HfAs1.7Se0.2.

Single crystals of HfAs(1.7)Se(0.2) are grown by chemical transport reaction and their chemical composition characterized in detail by various analytical methods.

ZT enhancement in solution-grown Sb(2-x)BixTe3 nanoplatelets.

We report a solution-processed, ligand-supported synthesis of 15-20 nm thick Sb(2-x)BixTe3 nanoplatelets. After complete ligand removal by a facile NH3-based etching procedure, the platelets are spark plasma sintered to a p-type nanostructured bulk material with preserved crystal grain sizes. Due to this nanostructure, the total thermal conductivity is reduced by 60% in combination with a reduction in electric conductivity of as low as 20% as compared to the bulk material demonstrating the feasibility of the phonon-glass electron-crystal concept.

Thermopower evidence for an abrupt Fermi surface change at the quantum critical point of YbRh2Si2.

We present low-temperature thermopower results, S(T), on the heavy-fermion compound YbRh2Si2 in the vicinity of its field-induced quantum critical point (QCP). At B=0, a logarithmic increase of -S(T)/T between 1 and 0.1 K reveals strong non-Fermi-liquid behavior.

Narrow band gap and enhanced thermoelectricity in FeSb2.

FeSb(2) was recently identified as a narrow-gap semiconductor with indications of strong electron-electron correlations. In this manuscript, we report on systematic thermoelectric investigation of a number of FeSb(2) single crystals with varying carrier concentrations, together with two isoelectronically substituted FeSb(2-x)As(x) samples (x = 0.01 and 0.