3D Dirac Electrons and Large Thermoelectric Properties in CoGe

Part of the Springer Theses book series (Springer Theses)


We have synthesized B20-type Co\(_{1-x}\)Fe\(_x\)Ge and Co\(_{1-y}\)Ni\(_y\)Ge by a high-pressure method and investigated the band-filling dependence of thermoelectric properties. Non-doped CoGe shows a large figure of merit (\(ZT\approx 0.11\)) due to its low resistivity and large negative Seebeck coefficient (\(S=-82\,\mathrm {\mu V/K}\)) at 300 K. S shows a sign change with increasing Fe concentration, yielding its maximum value (\(S=28\,\mathrm {\mu V/K}\) at 300 K) at \(x=0.2\). The Boltzmann transport model can explain semi-quantitatively the experimental results, from which we conclude that the large positive or negative S originates from the asymmetric band structure composed of the Dirac cone and the flat band with sharp bends around the Fermi energy (\(E_F\)).


Thermoelectric Property Seebeck Coefficient Flat Band Dirac Cone Phonon Thermal Conductivity 
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© Springer Japan 2015

Authors and Affiliations

  1. 1.Department of Applied PhysicsThe University of TokyoTokyoJapan

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