Unusual violation of the Wiedemann-Franz law at ultralow temperatures in topological compensated semimetals.

Thermal conductivity and electrical resistivity at ultralow temperatures and high magnetic fields are studied in the topological compensated semimetals TaAs, NbAs, and NdSb. A striking phenomenon is observed where the thermal conductivity shows a T scaling at very low temperatures, while the resistivity shows a T-independent residual term. This indicates a strong violation of the Wiedemann-Franz (WF) law, since the field dependence of κ shows that the low-temperature thermal conductivity is dominated by electronic transport.

Inelastic Electron Tunneling in 2H-Ta_{x}Nb_{1-x}Se_{2} Evidenced by Scanning Tunneling Spectroscopy.

We report a detailed study of tunneling spectra measured on 2H-Ta_{x}Nb_{1-x}Se_{2} (x=0∼0.1) single crystals using a low-temperature scanning tunneling microscope. The prominent gaplike feature, which has not been understood for a long time, was found to be accompanied by some "in-gap" fine structures.