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Magnetic and transport properties of the rare-earth-based Heusler phases R Pd Z and R Pd 2 Z <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" …

2005; American Physical Society; Volume: 72; Issue: 9 Linguagem: Inglês

10.1103/physrevb.72.094409

1550-235X

Krzysztof Gofryk, D. Kaczorowski, T. Plackowski, A. Leithe‐Jasper, Yu. Grin,

Advanced Thermoelectric Materials and Devices

Four series of ternary compounds $R\mathrm{Pd}\mathrm{Sb}$ $(R=\mathrm{Y},\mathrm{Ho},\mathrm{Er})$, $R\mathrm{Pd}\mathrm{Bi}$ $(R=\mathrm{Nd},\mathrm{Y},\mathrm{Dy},\mathrm{Ho},\mathrm{Er})$, $R{\mathrm{Pd}}_{2}\mathrm{Sb}$ $(R=\mathrm{Y},\mathrm{Gd}\ensuremath{-}\mathrm{Er})$, and $R{\mathrm{Pd}}_{2}\mathrm{Bi}$ $(R=\mathrm{Y},\mathrm{Dy}\ensuremath{-}\mathrm{Er})$ were studied by means of magnetization, magnetic susceptibility, electrical resistivity, magnetoresistivity, thermoelectric power, and Hall effect measurements, performed in the temperature range $1.5--300\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and in magnetic fields up to $12\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. All these ternaries, except for diamagnetic Y-based phases, exhibit localized magnetism of ${R}^{3+}$ ions, and a few of them order antiferromagnetically at low temperatures $({T}_{N}=2--14\phantom{\rule{0.3em}{0ex}}\mathrm{K})$. The equiatomic compounds show half-metallic conductivity due to the formation of narrow gaps in their electronic band structures near the Fermi energy. Their Seebeck coefficient at room temperature is exceptionally high (S up to $200\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{V}∕\mathrm{K}$), being promising for thermoelectric applications. In contrast, all the 1:2:1 phases are semimetals and their thermoelectric power is much lower (maximum S of $10--25\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{V}∕\mathrm{K}$). The Hall effect in the compounds studied corroborates complex character of their electronic structure with multiple electron and hole bands with different temperature and magnetic field variations of carrier concentrations and their mobilities.