NMR study of the electronic properties and crystal structure of the semiconducting compound<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Al</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Ru

Hill, E. A.; Volkov, Pavel A.; Poon, S. J.; Wu, Yue

doi:10.1103/physrevb.51.4865

Cited by 8 publications

(29 citation statements)

References 11 publications

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“…The temperature variation of 93 Nb 1/T 1 of Ru 2 NbGa is illustrated in Fig. 3 and then a rapid rise above 220 K. Similar features have been found in 51 V 1/T 1 of Fe 2 VAl and Fe 2 VGa [12,13,39], 27 Al 1/T 1 of RuAl 2 and CaAl 2 Si 2 [40,41], as well as 59 Co 1/T 1 of (La, Ca) x Co 4 Sb 12 and CoTiSb [42][43][44]. Those observations have been well described by the Korringa process together with an additional contribution from activated behavior.…”

Section: B Nmr Measurementssupporting

confidence: 76%

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

et al. 2016

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The Heusler-type compound of Ru 2 NbGa has been successfully synthesized. X-ray analysis confirms that Ru 2 NbGa crystallizes in a cubic L2 1 structure. The electronic properties of Ru 2 NbGa have been characterized by means of the transport and nuclear magnetic resonance (NMR) measurements. The temperature dependence of the electrical resistivity exhibits a typical semimetallic behavior. The NMR spin-lattice relaxation rate shows activated behavior at higher temperatures, attributing to the thermally excited carriers across a pseudogap. We have also deduced a low Fermi-level density of states (DOS), being consistent with the semimetallic characteristic for Ru 2 NbGa. In addition, we have performed first-principles total-energy calculations including G 0 W 0 and GW 0 corrections for band gaps to investigate the electronic band structure of Ru 2 NbGa. The calculated result reveals an indirect overlap between electron and hole pockets that leads to a residual DOS at the Fermi level, providing a consistent explanation for the experimental observations.

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Section: B Nmr Measurementssupporting

confidence: 76%

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

et al. 2016

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“…6, we plot 1/T 1 T vs T for demonstrating a pronounced increase beyond the Korringa relation (constant 1/T 1 T ) [49]. Similar features have been found in 27 Al 1/T 1 of semimetallic CaAl 2 Si 2 , SrAl 2 Si 2 , and RuAl 2 [50][51][52]. By analogy, the T -dependent 1/T 1 of Ru 2 TaAl can be expressed by CT + AT 2 exp(−E A /2k B T ), where C, A, and E A are fitting parameters.…”

Section: Al Nuclear Magnetic Resonancesupporting

confidence: 70%

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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“…The decay of the spin echo without MAS is due to 31 P-31 P dipolar coupling, whereas this decay mechanism is removed by rotor synchronized MAS as demonstrated by the solid diamonds and triangles in Figure 7, respectively. The decay of the 31 P spin echo in Figure 7 for static Ca 14 AlP 11 is a good measure of the 31 P- 31 …”

Section: Discussionmentioning

confidence: 99%

“…The samples were packed into zirconium oxide rotors in a drybox and spun with dry N 2 gas. The low spinning speed (1.6-7 kHz) 31 P MAS spectra were obtained with a Chemagnetics MAS probe equipped for 7.5 mm o.d. rotors having O-ring sealed PTFE plugs.…”

Section: Methodsmentioning

confidence: 99%

Magnetic Resonance Study of a Series of Phosphorus-Containing Zintl Compounds: Ca₁₄AlP₁₁, Ca₁₄MnP₁₁, and Eu₁₄MnP₁₁

et al. 2002

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The compounds Ca 14 AlP 11 , Ca 14 MnP 11 , and Eu 14 MnP 11 have been synthesized and are isostructural to the Zintl compound, Ca 14 AlSb 11 . Eu 14 MnP 11 is a ferromagnet showing colossal magnetoresistance at T C ) 52 K, Ca 14 MnP 11 shows paramagnetic behavior down to 5 K, and Ca 14 AlP 11 is nonmagnetic. The formula unit for these Zintl compounds is A 14 MPn 11 and comprises 14 A cations, a MPn 4 tetrahedron, four isolated Pn anions, and a Pn 3 linear unit. The central Pn of the Pn 3 unit is believed to be positionally disordered, and it has been speculated that the disorder is static rather than dynamic. To address this issue, 31 P solidstate NMR was applied to these new compounds to provide insight into the magnetic ordering and structural changes. The NMR chemical shift anisotropy and the dipolar coupling for the 31 P nuclei as well as the quadrupolar coupling for the 27 Al nucleus in the diamagnetic compound Ca 14 AlP 11 provide structural details consistent with the Zintl structure. Wideline 31 P NMR and EPR were applied to the paramagnetic compounds Ca 14 MnP 11 and Eu 14 MnP 11 to obtain similar structural information. The lack of any EPR spectra for the Eu-substituted compound below 50 K confirms the assigned paramagnetic-to-ferromagnetic transition temperature of 52 K. Hyperfine couplings in the Eu-substituted compound suggests localization of the electron density above 50 K.

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NMR study of the electronic properties and crystal structure of the semiconducting compoundAl2Ru

Cited by 8 publications

References 11 publications

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

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

Magnetic Resonance Study of a Series of Phosphorus-Containing Zintl Compounds: Ca₁₄AlP₁₁, Ca₁₄MnP₁₁, and Eu₁₄MnP₁₁

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NMR study of the electronic properties and crystal structure of the semiconducting compoundAl2Ru

Cited by 8 publications

References 11 publications

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

Ru2NbGa : A Heusler-type compound with semimetallic characteristics

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

Magnetic Resonance Study of a Series of Phosphorus-Containing Zintl Compounds: Ca14AlP11, Ca14MnP11, and Eu14MnP11

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Magnetic Resonance Study of a Series of Phosphorus-Containing Zintl Compounds: Ca₁₄AlP₁₁, Ca₁₄MnP₁₁, and Eu₁₄MnP₁₁