<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">Ru</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mtext>NbGa</mml:mtext></mml:math>
: A Heusler-type compound with semimetallic characteristics

Kuo, C. N.; Lee, H. W.; Wei, C. M.; Lin, Yan-Min; Kuo, Y. K.; Lue, Chin‐Shan

doi:10.1103/physrevb.94.205116

Cited by 21 publications

(12 citation statements)

References 58 publications

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“…Due to its finite residual resistivity at low temperatures, this material should be classified as a semimetal. Similar ρ(T ) features have been found in other ruthenium-based semimetallic Heusler compounds such as Ru 2 NbGa [28]. The activated transport behavior observed in Ru 2 TaAl can be realized as the thermally excited carriers across the pseudogap near E F , in analogy to the case of Ru 2 NbGa.…”

Section: A Electrical Transport and Thermoelectric Propertiessupporting

confidence: 75%

“…Whereas, the GW methods [57], by calculating dynamically screened Coulomb interaction (W ) and Green's functions (G), have included the many-body interaction and thus will produce reliable band structures. Taking our previous studies related to Ru 2 NbGa as an example [28], the band structures obtained from DFT frameworks [Perdew-Burke-Ernzerhof (PBE) and HSE06) [58,59] are controversial while the results obtained from the GW 0 approximation [60] using either PBE or HSE06 initial wave functions have yielded consistent and reliable band structures. Based on the previous work [28], we have performed the first-principles total-energy calculations with GW 0 or G 0 W 0 corrections [60,61] for the band gaps using PBE initial wave functions.…”

Section: Electronic Structure Calculationsmentioning

confidence: 99%

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Semimetallic behavior in Heusler-type Ru2TaAl and thermoelectric performance improved by off-stoichiometry

et al. 2017

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We report a study of the temperature-dependent electrical resistivity, Seebeck coefficient, thermal conductivity, specific heat, and 27 Al nuclear magnetic resonance (NMR) in Heusler-type Ru 2 TaAl, to shed light on its semimetallic behavior. While the temperature dependence of the electrical resistivity exhibits semiconductorlike behavior, the analysis of low-temperature specific heat reveals a residual Fermi-level density of states (DOS). Both observations can be realized by means of a semimetallic scenario with the Fermi energy located in the pseudogap of the electronic DOS. The NMR Knight shift and spin-lattice relaxation rate show activated behavior at higher temperatures, attributing to the thermally excited carriers across a pseudogap in Ru 2 TaAl. From the first-principles band structure calculations, we further provide a clear picture that an indirect overlap between electron and hole pockets is responsible for the formation of a pseudogap in the vicinity of the Fermi level of Ru 2 TaAl. In addition, an effort for improving the thermoelectric performance of Ru 2 TaAl has been made by investigating the thermoelectric properties of Ru 1.95 Ta 1.05 Al. We found significant enhancements in the electrical conductivity and Seebeck coefficient and marked reduction in the thermal conductivity via the off-stoichiometric approach. This leads to an increase in the figure-of-merit ZT value from 6.1 × 10 −4 in Ru 2 TaAl to 3.4 × 10 −3 in Ru 1.95 Ta 1.05 Al at room temperature. In this respect, a further improvement of thermoelectric performance based on Ru 2 TaAl through other off-stoichiometric attempts is highly probable.

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Section: A Electrical Transport and Thermoelectric Propertiessupporting

confidence: 75%

Section: Electronic Structure Calculationsmentioning

confidence: 99%

Semimetallic behavior in Heusler-type Ru2TaAl and thermoelectric performance improved by off-stoichiometry

et al. 2017

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“…Since then, many studies have been dedicated to investigate the electronic and magnetic properties of ternary and quaternary full-Heusler compounds. It has been revealed that full-Heusler compounds exhibit a variety of electronic properties; they exhibit the properties of semiconductors [9][10][11][12][13][14][15][16][17][18], spingapless semiconductors (SGSs) [19][20][21][22][23][24][25][26], semimetals [27][28][29], metals [30][31][32][33][34] and half-metals (HMs) [32,. Considering the magnetic properties, they have been reported to exhibit nonmagnetism [9][10][11][14][15][16][17][18], ferromagnetism [12, 19-24, 30-33, 36-46, 48-58, 61-66, 68-78], ferrimagnetism [13,30,35,47,59,60,67] and antiferromagnetism [25,26,34].…”

Section: Crystal Structures and Magnetic Properties Of Full-heusler Cmentioning

confidence: 99%

Magnetic Full-Heusler Compounds for Thermoelectric Applications

Hayashi¹,

Li²,

Eguchi³

et al. 2021

Magnetic Materials and Magnetic Levitation

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Full-Heusler compounds exhibit a variety of magnetic properties such as non-magnetism, ferromagnetism, ferrimagnetism and anti-ferromagnetism. In recent years, they have attracted significant attention as potential thermoelectric (TE) materials that convert thermal energy directly into electricity. This chapter reviews the theoretical and experimental studies on the TE properties of magnetic full-Heusler compounds. In Section 1, a brief outline of TE power generation is described. Section 2 introduces the crystal structures and magnetic properties of full-Heusler compounds. The TE properties of full-Heusler compounds are presented in Sections 3 and 4. The relationship between magnetism, TE properties and order degree of full-Heusler compounds is elaborated.

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“…This valence electron count (VEC) is frequently used to classify different groups of Heuslers. For example, for VEC = 24 semimetallic behavior is expected 15 with vanishing net magnetic moment 16 – 22 . Adding three electrons to the system (VEC = 27) often reveals superconductivity, including the Heusler compounds containing magnetic rare earth metals, i.e.…”

Section: Introductionmentioning

confidence: 99%

Superconductivity in LiGa2Ir Heusler type compound with VEC = 16

Górnicka

Kuderowicz

Winiarski

et al. 2021

Sci Rep

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Polycrystalline LiGa2Ir has been prepared by a solid state reaction method. A Rietveld refinement of powder x-ray diffraction data confirms a previously reported Heusler-type crystal structure (space group Fm-3m, No. 225) with lattice parameter a = 6.0322(1) Å. The normal and superconducting state properties were studied by magnetic susceptibility, heat capacity, and electrical resistivity techniques. A bulk superconductivity with Tc = 2.94 K was confirmed by detailed heat capacity studies. The measurements indicate that LiGa2Ir is a weak-coupling type-II superconductor ($${\uplambda }$$ λ e–p = 0.57, $${\Delta }$$ Δ C/$${\upgamma }$$ γ Tc = 1.4). Electronic structure, lattice dynamics, and the electron–phonon interaction are studied from first principles calculations. Ir and two Ga atoms equally contribute to the Fermi surface with a minor contribution from Li. The phonon spectrum contains separated high frequency Li modes, which are seen clearly as an Einstein-like contribution in the specific heat. The calculated electron–phonon coupling constant $${\uplambda }$$ λ e–p = 0.68 confirms the electron–phonon mechanism for the superconductivity. LiGa2Ir and recently reported isoelectronic LiGa2Rh are the only two known representatives of the Heusler superconductors with the valence electron count VEC = 16.

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Ru2NbGa : A Heusler-type compound with semimetallic characteristics

Cited by 21 publications

References 58 publications

Semimetallic behavior in Heusler-type Ru2TaAl and thermoelectric performance improved by off-stoichiometry

Semimetallic behavior in Heusler-type Ru2TaAl and thermoelectric performance improved by off-stoichiometry

Magnetic Full-Heusler Compounds for Thermoelectric Applications

Superconductivity in LiGa2Ir Heusler type compound with VEC = 16

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