New Heusler-type Compound of Ru2NbGa with Semimetallic Behavior
C. N. Kuo1*, H. W. Lee2, C. -M. Wei2, Y. H. Lin3, Y. K. Kuo3, C. S. Lue1
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
2Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, Taiwan
3Department of Physics, National Dong Hwa University, Hualien, Taiwan
* presenting author:Chia-Nung Kuo,
The Huesler Compound with X2YZ stoichiometry has been of great interest due to its various physical properties and potential applications. We have synthesized the new Huesler compound Ru2NbGa by arc-melting, characterized its transport and NMR properties, and calculated its electronic band structure by First-principles total-energy calculations. The temperature dependence of the electrical resistivity exhibits a typical semimetallic behavior. The Seebeck coefficient of about 20 μV K-1 at 300 K is comparable to those thermoelectric candidates of Fe2VAl and Fe2VGa. The NMR spin-lattice relaxation rate shows activated behavior at higher temperatures, attributing to the thermally excited carriers across a pseudogap. The tiny density of state and pseudogap derived from the NMR study are in fairly good agreement with the theoretical result. Since the thermoelectric features of Ru2NbGa behave in a similar manner to those observed in the semimetallic Heusler compounds, the Ru-based Huesler compounds may provide a platform for searching novel thermoelectric materials.

Keywords: Huesler compound, thermometric material, NMR