Autor: Tran, V. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Unusual Electron Transport Properties of $U_{0.05}Y_{0.95}Al_2$
Autorzy:: Tran, V.
Tematy:: 72.15.Jf
72.15.Qm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813710.pdf Link otwiera się w nowym oknie
Opis:: We report a detailed study of the resistivity (ρ(T)) and thermoelectric power (S(T)) of the alloy $U_{0.05}Y_{0.95}Al_2$, which crystallises in the cubic $MgCu_2$-type structure. The resistivity is found to follow ρ(T) ∝ ln T between 15 and 40 K and a quasi-linear temperature dependence $-T^{1.16}$ for T <10 K. At a magnetic field of 9 T a Kondo-type maximum occurs in the resistivity data at 7 K, below which the Fermi liquid behaviour (ρ(T) ∝ $T^2$) is recovered. S(T)/T shows a $T^{0.5}$ power law for T <12 K. The low-temperature unconventional features observed in $U_{0.05}Y_{0.95}Al_2$ are presumably due to the presence of the two-channel Kondo effect.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Electronic Structure of Th₇Ru₃
Autorzy:: Sahakyan, M.
Tran, V.
Tematy:: 71.15.Mb
71.15.Rf
71.18.+y
71.20.-b
74.20.Mn
74.20.Rp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1031027.pdf Link otwiera się w nowym oknie
Opis:: We report the results of scalar and fully relativistic electronic structure calculations for nonsuperconducting Th₇Ru₃, using the full-potential linearized-muffin-thin-orbital and full-potential linearized augmented-plane wave methods. The obtained data, including electronic band structures, density of states, Fermi surfaces and electron localization function, reveal the presence of anisotropic spin-orbit coupling but its strength, exposed by splitting energies of the order of 10-40 meV, is much weaker as compared to those of Th₇Fe₃ or Th₇Co₃ superconductors. Moreover, the lack of Van Hove singularity near the Fermi level underscores a key point of the non-occurrence of superconductivity in the studied compound.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: $Ru_3Sn_7$: Phonon Reference for Superconducting $Mo_3Sb_7$
Autorzy:: Tran, V.
Miiller, W.
Tematy:: 65.40.-b
72.15.Eb
74.25.Kc
74.25.Bt
72.15.Qm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1810300.pdf Link otwiera się w nowym oknie
Opis:: In order to search for phonon reference for dimer-gapped superconducting $Mo_3Sb_7$, measurements of specific heat $(C_p(T))$ and electrical resistivity (ρ(T)) of $Ru_3Sn_7$ were performed in the temperature range 2-300 K. The phonon part of $C_p(T)$ and ρ(T) of $Ru_3Sn_7$ can satisfactorily be explained describing the spectrum with one Einstein and two Debye modes. We found $Θp_{E}$ ≈ 100 K, $Θp_{D1}$ ≈ 185 K and $Θp_{D2}$ ≈298 K. The magnetic specific heat of $Mo_3Sb_7$ exhibits a sharp maximum at T*= 50 K, below which follows a gap function. Magnetic resistivity increases as -lnT with decreasing temperature and shows maximum at T*.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Synthesis and Characterization of the Superconductor $Mo_3Sb_7$
Autorzy:: Tran, V.
Bukowski, Z.
Tematy:: 74.25.Bt
74.70.-b; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1812274.pdf Link otwiera się w nowym oknie
Opis:: We synthesized a polycrystalline sample of the superconductor $Mo_3Sb_7$ and characterized its basic properties by measurements of magnetization, electrical resistivity and specific heat. The measurements establish a superconducting phase transition at $T_c$=2.25 (0.05) K. In applied magnetic fields, the magnetization and resistivity show the behavior of type-II superconductor. From the specific heat measurement, the electronic specific heat coefficient,γ, specific heat jump at $T_c,$ $ΔC(T_c)//γT_c,$ and the Debye temperature $Θ_D$, are evaluated to be 34.5 mJ/(mol $K^2$), 1.56 and 283 K, respectively. From analysis of the specific heat data we suggest that this compound belongs to an intermediate strong coupling regime in the BCS context. The observed enhancement in theγ-value suggests a substantial contribution of Mo-4d-electrons to the density of states. Our experimental data do not support interpretation of superconductivity in $Mo_3Sb_7$ in terms of neither unconventional superconductivity or spin fluctuations proposed previously.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Intriguing Magnetoresistivity of $URh_{0.62}Ru_{0.38}Ge$ in the Non-Fermi Liquid Regime
Autorzy:: Miiller, W.
Tran, V.
Tematy:: 71.10.Hf
71.20.Lp
71.27.+a; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1810409.pdf Link otwiera się w nowym oknie
Opis:: Magnetoresistivity of $URh_{0.62}Ru_{0.38}Ge$ solid solution was measured in the temperature range 0.35-300 K and in magnetic fields up to 9 T. For the studied system, which lies on the border of ferromagnetism, we observe positive magnetoresistivity in the non-Fermi liquid regime. The finding is in striking disagreement with scenario predicted for ferromagnetic quantum critical point.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Electronic Band Structure of Ru₃Sn₇
Autorzy:: Sahakyan, M.
Tran, V.
Tematy:: 71.15.Ap
31.15.A-
74.20.Pq; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1385432.pdf Link otwiera się w nowym oknie
Opis:: The first-principle band structure calculations for Ru₃Sn₇ and Mo₃Sb₇ were carried out using the full-potential linearized muffin tin orbital method. It was shown that the valence band contribution is mainly due to the 4d electrons of Ru(Mo), while the contribution from the 5p-Sn(Sb) orbitals is relatively small. Furthermore, the 4d and 5p orbitals located near the Fermi level have the non-hybridized characters, thus presumably contributing independently to the total density of states. A comparison of the density of states of two compounds reveals an essential difference in the structures and magnitudes. We estimated the mass enhancement factor and Stoner product and discussed these differences regarding to electronic and magnetic behaviour of these compounds.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Non-Fermi-Liquid State in $URu_{0.68}Pd_{0.32}Ge$
Autorzy:: Tran, V.
Gralak, D.
Tematy:: 71.27.+a
75.30.Mb
75.40.Cx
75.45.+j; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1385459.pdf Link otwiera się w nowym oknie
Opis:: We report the measurements of dc-magnetization (M), specific heat $(C_{p})$ and electrical resistivity (ρ) of an intermetallic $URu_{0.68}Pd_{0.32}Ge$, that lies at the border between nonmagnetic and magnetic regimes in the magnetic phase diagram of solid solutions $URu_{1-x}Pd_{x}Ge$. The studied composition shows enhanced dc-magnetic susceptibility χ(T) and the Sommerfeld ratio $C_{p}(T)$/T at low temperatures. Below 4 K χ(T), $C_{p}(T)$/T and ρ(T) can be described by χ(T) ∝ $T^{-0.48}$, $C_{p}(T)$/T ∝ √T and ρ(T) ∝ c ln(T)+$AT^{3/2}$, respectively. These observations provide an evidence that $URu_{0.68}Pd_{0.32}Ge$ is a moderately heavy-fermion system with an electronic ground state of non-Fermi liquid character. We found non-linear effect of the magnetization and a large value of the Wilson ratio, which are consistent with the interpretation in terms of magnetic instability.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Transport Properties of the U$\text{}_{1-x}$Th$\text{}_{x}$Pt System
Autorzy:: Tran, V. H.
Troć, R.
Tematy:: 72.15.Eb
72.15.Gd
75.70.Pa; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2013010.pdf Link otwiera się w nowym oknie
Opis:: We present the results of measurements of electrical resistivity (ρ(T)) and magnetoresistance (Δϱ/ϱ$\text{}_{0}$(T)) on the solid solutions U$\text{}_{1-x}$Th$\text{}_{x}$Pt (x=0-0.8). The Curie temperature (T$\text{}_{c}$=21 K) found for the parent compound UPt, is steadily reduced upon the Th-substitution. The ρ(T) and Δϱ/ϱ$\text{}_{0}$(T) functions provide evidence of electron scattering due to spin fluctuations. The most interesting feature of Δϱ/ϱ$\text{}_{0}$ is its high value of about -22% found for UPt and U$\text{}_{0.9}$Th$\text{}_{0.1}$Pt at their T$\text{}_{c}$ and B=8 T. For samples with x ≥ 0.2, the value of Δϱ/ϱ$\text{}_{0}$ at 4 K and 8 T increases with x and becomes positive for Th-composition x >= 0.6.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Anomalous Magnetic Properties of URuGa
Autorzy:: Tran, V. H.
Troć, R.
Tematy:: 72.15.Qm
75.40.Cx
75.80.+q; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1964580.pdf Link otwiera się w nowym oknie
Opis:: We present data of the magnetic susceptibility χ(T) and electrical resistivity ρ(T) for the hexagonal URuGa (space group P6̅2m). Below 7 K, χ increases rapidly and the data can be described by the expression χ(T) = χ(0)(1-a√T). ρ(T) in zero field follows the activated form: ρ(T)∼ exp(E$\text{}_{a}$/2k$\text{}_{B}$T ) with E$\text{}_{a}$ = 1.9 meV. In an applied magnetic field of 1 T, the resistivity varies as ρ(T)∼ bT. Between 18 and 250 K the resistivity is linear in -lnT and consistent with a Kondo-like effect.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Hybridization Effects in UCu$\text{}_{5-x}$Au$\text{}_{x}$ Compounds
Autorzy:: Tran, V. H.
Troć, R.
Tematy:: 71.28.+d; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1929857.pdf Link otwiera się w nowym oknie
Opis:: We review the results of bulk and neutron diffraction measurements on the UCu$\text{}_{5-x}$Au$\text{}_{x}$ system crystallizing in the cubic AuBe$\text{}_{5}$-type structure. The observed properties may be understood in the light of competition between Kondo effect and RKKY exchange interactions. Effects of 5f-ligand hybridization between the U-atoms occupying the 4a-sites and the Au- or/and Cu-atoms placed at the 4c- and 16e-positions, respectively, are supposed to be different. We show that the prefential occupation of 4c-sites by Au has a marked effect on the magnetic properties of the investigated system.
Dostawca treści:: Biblioteka Nauki

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