Abrupt symmetry decrease in the ThT2Al20 alloys (T = 3d transition metal)

Uziel, A.; Bram, A.; Venkert, A.; Kiv, A.; Fuks, David; Meshi, Louisa

doi:10.1016/j.jallcom.2015.06.216

Cited by 15 publications

(17 citation statements)

References 31 publications

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“…Furthermore, for the orthorhombic ThFe 2 Al 10 phase, the authors also predicted a zero total magnetic moment on Fe atoms, while for the unstable cubic phase they found a small Fe-moment, which, according to the authors, provides another proof of instability of the latter phase. Also, our fully relativistic results, as mentioned in subsection 2.2, based on somewhat different from those given in [27] crystallographic data (set 1), have confirmed that the Fe atoms cannot become magnetically ordered even at T = 0 K. As shown below, the latter result may contradict the experimental data.…”

Section: Electronic Structurecontrasting

confidence: 47%

“…In turn, the five different Al atoms coordinate in irregular polyhedra consisting of U, Fe, or Al atoms with CN ranging from 12 to 14. It is interesting to note that a similar coordination around the T atom (T = Ti, V, and Cr) is formed in the case of ThT 2 Al 20 series, crystallizing in the cubic CeCr 2 Al 20 type of structure [27]. In contrast to ThFe 2 Al 10 , the coordination sphere there is a regular icosahedron T-Al 12 , which is, however, unstable when T = Fe.…”

Section: Crystal Structure Refinementmentioning

confidence: 85%

“…Very recently, Uziel et al [27] performed total energy calculations using a scalar relativistic FP-LAPW method within GGA as implemented in the Wien2k code for the cubic and orthorhombic phases of ThT 2 Al x (x = 20 and 10, respectively) considering different atoms of transition metals T. However, they did not show any electronic structure results. Based on the total energy difference, they proved only that the orthorhombic Cmcm crystal structure is stable for ThFe 2 Al 10 as for ThFe 2 Al 20 .…”

Section: Electronic Structurementioning

confidence: 99%

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Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Troć

Wawryk

Gajek

et al. 2017

Journal of Alloys and Compounds

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We have grown single crystals of ThFe 2 Al 10 and used them for the refinement of its crystal structure. From the specific heat data, we determined the phonon components, that is, the Debye and Einstein modes, for Th-and Ubased isostructural aluminides. To approximate the Sommerfeld coefficients, we had to include the T 3 lnT term characteristic of spin-fluctuations originating from the Fe-sublattice. The roughly estimated spin-fluctuation temperature is about 11 K. ThFe 2 Al 10 is a weakly temperature-dependent Pauli-paramagnet. However, at lower temperatures the ferromagnetic correlations are observed, which signals that the system drives to quantum criticality. The distinct minimum in electrical resistivity observed at about 20 K suggests a realization of a nonmagnetic two-channel Kondo-effect in ThFe 2 Al 10 , as discussed for ThAsSe [Phys. Rev. Lett. 94, 236603 (2005)], for example. The [ρ(T) -ρ min ] versus T curves of ThFe 2 Al 10 , determined along the a-and c-axes, were used to subtract the phonon contributions from the corresponding ρ(T) a,c of UFe 2 Al 10 . The resulting magnetic part of the average ρ m (T) av curve was then analysed in terms of the influence of the crystal field effect on the transport properties. However, to obtain agreement with the experiment, we had to take into account another effect, namely the Kondo-like one. This kind of probe has been applied for the first time in the case of uranium compounds. Based on the magnetoresistivity, we have revealed the anisotropic low-frequency vibrations of the Th atom (located in its [Al 16 Fe 4 ] cage) interacting with the conduction band, the phenomenon revealed previously in the metallic UB 12 [Phil. Mag. B 95, 2343]. Furthermore, fully relativistic band structure calculations performed for ThFe 2 Al 10 revealed its metallic-like character with a similarly large contribution of the Fe 3d electrons at the Fermi level as predicted previously for its 5f-electron analogue UFe 2 Al 10 . In addition, there are substantial differences between their Fermi surfaces.

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Section: Electronic Structurecontrasting

confidence: 47%

Section: Crystal Structure Refinementmentioning

confidence: 85%

Section: Electronic Structurementioning

confidence: 99%

See 1 more Smart Citation

Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Troć

Wawryk

Gajek

et al. 2017

Journal of Alloys and Compounds

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“…This suggested that the real composition could be slightly sub-stoichiometric. Recently Uziel et al [17] studied ThT 2 Al 20 (T = Ti-Fe) materials, revealing that the CeCr 2 Al 20 -type phase is obtained only with T = Ti, V, Cr. The only known Mn-bearing CeCr 2 Al 20 -type aluminide, UMn 2 Al 20 , was established to exhibit an itinerant ferromagnetic behavior [5,6].…”

Section: (A) (B)mentioning

confidence: 99%

Synthesis and properties of AxV2Al20 (A = Th, U, Np, Pu) ternary actinide aluminides

Winiarski

Griveau

Colineau

et al. 2017

Journal of Alloys and Compounds

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Polycrystalline samples of A x V 2 Al 20 (A = Ce, Th, U, Np, Pu; 0.7 ≤ x ≤ 1.0) actinide intermetallics were synthesized using the arcmelting method. Crystal structure studies were performed by means of powder x-ray diffraction and the Rietveld refinement method. All studied compounds crystallize in the CeCr 2 Al 20 -type structure (space group Fd-3m, no. 227) with the actinide or Ce atom located in the oversized cage formed by Al atoms. Comparison of the crystallographic results with the reported data for LnV 2 Al 20 (Ln = lanthanoids) counterparts reveals distinctly different behavior of the lanthanide-and actinide-bearing compounds. This difference is suggested to be caused by fairly localized character of the 4f electrons, whereas itinerant character of the 5f electrons is likely seen for U-and Npcontaining phases. Magnetic susceptibility and specific heat measurements did not reveal any magnetic ordering in U 0.8 V 2 Al 20 , Np 0.8 V 2 Al 20 and Pu 0.8 V 2 Al 20 down to 2.5 K. A small anomaly in low-temperature specific heat of Ce 0.8 V 2 Al 20 , U 0.8 V 2 Al 20 , and Np 0.8 V 2 Al 20 is observed, likely arising from a low-energy Einstein mode.

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“…The atomic positions were found to be the same as in the Mg 3 Cr 2 Al 18 [21] and ZrZn 22 [22,23] intermetallics described earlier. In further studies, CeCr 2 Al 20 -type (1-2-20) aluminides were synthesized with transition metals of groups 5 and 6 as well with titanium and manganese [24,25,26,27,28,29,30,31,32]. Depending on the transition metal, different electropositive elements (rareearth elements, actinides, and Ca) could be introduced to the 8a position, with compounds containing 4d and 5d metals generally forming only with the early lanthanides (La-Sm), Ca, and U [27].…”

Section: Introductionmentioning

confidence: 99%

Rattling-enhanced superconductivity inMV2Al20(M=Sc,Lu
Winiarski¹,
Wiendlocha²,
Sternik³
et al. 2016
Phys. Rev. B
41
2
22
0
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Polycrystalline samples of four intermetallic compounds: MV 2 Al 20 (M = Sc, Y, La, and Lu) were synthesized using an arc-melting technique. The crystal structures were analyzed by means of powder xray diffraction and Rietveld analysis, and the physical properties were studied by means of heat capacity, electrical resistivity and magnetic susceptibility measurements down to 0.4 K. For ScV 2 Al 20 , LuV 2 Al 20 , and YV 2 Al 20 , superconductivity was observed with critical temperatures T c = 1.00 K, 0.57 K, and 0.60 K, respectively. Superconductivity for the Lu compound is reported for the first time. Theoretical calculations of the electronic and phonon structures were conducted in order to analyze the superconductivity and dynamics in ScV 2 Al 20 , YV 2 Al 20 , and LuV 2 Al 20 and to explain the lack of a superconducting transition in LaV 2 Al 20 down to 0.4 K. The results of the experimental and theoretical studies show that all the compounds are weakly-coupled type II BCS superconductors, and reveal the importance of the M-atom anharmonic "rattling" modes for the superconductivity in these materials, which seem to enhance T c , especially for ScV 2 Al 20 .

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Abrupt symmetry decrease in the ThT2Al20 alloys (T = 3d transition metal)

Cited by 15 publications

References 31 publications

Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Synthesis and properties of AxV2Al20 (A = Th, U, Np, Pu) ternary actinide aluminides

Rattling-enhanced superconductivity inMV2Al20(M=Sc,Lu
Winiarski¹,
Wiendlocha²,
Sternik³
et al. 2016
Phys. Rev. B
41
2
22
0
View full text Add to dashboard Cite

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Abrupt symmetry decrease in the ThT2Al20 alloys (T = 3d transition metal)

Cited by 15 publications

References 31 publications

Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Comparative studies of the cage systems ThFe2Al10 and UFe2Al10

Synthesis and properties of AxV2Al20 (A = Th, U, Np, Pu) ternary actinide aluminides

Rattling-enhanced superconductivity inMV2Al20(M=Sc,LuWiniarski1, Wiendlocha2, Sternik3 et al. 2016Phys. Rev. B412220View full textAdd to dashboardCite

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About

Rattling-enhanced superconductivity inMV2Al20(M=Sc,Lu
Winiarski¹,
Wiendlocha²,
Sternik³
et al. 2016
Phys. Rev. B
41
2
22
0
View full text Add to dashboard Cite