High-Field Superconductivity of Carbides

Fink, H.J.; Thorsen, A. C.; Parker, E.R.; Zackay, V.F.; Toth, L. E.

doi:10.1103/physrev.138.a1170

Cited by 42 publications

(21 citation statements)

References 12 publications

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“…[2][3][4][5] Recently it has attracted renewed attention, 6-10 because its cubic β-Mn-type crystal structure does not contain a center of inversion. In such noncentrosymmetric superconductors, as first discussed for CePt 3 Si, 11 the electron pairing process is described to be a mixture of spin-singlet and spin-triplet states. 12,13 The question whether Mo 3 Al 2 C can be classified as a conventional or unconventional superconductor remains unresolved according to very recent investigations.…”

Section: Introductionmentioning

confidence: 99%

Density functional theory study of phase stability, vibrational, and electronic properties of Mo3Al2C

2012

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Based on density functional theory the noncentrosymmetric superconductor Mo3Al2C in its well established β-Mn type (P4132) crystal structure is investigated. In particular, its thermodynamical and dynamical stabilities are studied by calculating lattice vibrations within the harmonic approximation. It is found that the fully stoichiometric compound is dynamically unstable. However, compounds with carbon vacancies, i.e., Mo3Al2C1−x, can be dynamically stabilized for vacancy concentrations x > 0.09. By means of a simple thermodynamical model we estimate x ∼ 0.13 − 0.14 for Mo3Al2C1−x at the experimental preparation temperatures. The influence of the carbon vacancy concentration on the electronic structure is investigated.

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Section: Introductionmentioning

confidence: 99%

Density functional theory study of phase stability, vibrational, and electronic properties of Mo3Al2C

2012

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“…The origin of the superconductivity at T cu (H) may be due to Ta-C layers in Ta 2 S 2 C. According to Giorgi et al,12 the critical temperature T c of the pristine TaC 1−x increases with decreasing x and is equal to 9.0 K at x = 0.019. Fink et al13 have reported that the values of H c1 and H c2 at T = 1.2 K for TaC are 220 Oe and 4.6 kOe. These values are in good agreement with the values of T cu and H(u)…”

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confidence: 99%

Successive superconducting transitions and Anderson localization effect inTa2S2C

Walter

Suzuki

2004

Phys. Rev. B

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A complex carbide Ta2S2C consists of van der Waals (vdw)-bonded layers with a stacking sequence · · · C-Ta-S-vdw-S-Ta-C-· · · along the c axis. The magnetic properties of this compound have been studied from DC and AC magnetic susceptibility. Ta2S2C undergoes successive superconducting transitions of a hierachical nature at T cl = 3.61 ± 0.01 K [H (l) c1 (0) = 28 ± 2 Oe and H (l) c2 (0) = 7.7 ± 0.2 kOe] and Tcu = 9.0 ± 0.2 K [H (u) c2 (0) = 6.0 ± 0.3 kOe]. The intermediate phase between Tcu and T cl , where δχ(= χF C − χZF C ) ≈ 0, is an intra-grain superconductive state occurring in the Ta-C layers in Ta2S2C. The low temperature phase below T cl , where δχ clearly appears, is an inter-grain superconductive state. The magnetic susceptibility at H well above H (l)c2 (0) is described by a sum of a diamagnetic susceptibility and a Curie-like behavior. The latter is due to the localized magnetic moments of conduction electrons associated with the Anderson localization effect, occurring in the 1T-TaS2 type structure in Ta2S2C.

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“…Later, Fink et al reported the upper critical field (H c2 ) = 15.6 T at 1.2 K, which was determined from critical current density measurements 27 . From the experimentally determined values of the upper critical field (H c2 ), the normal-state resistivity (ρ n ), the critical current density (J c ), and the transition temperature (T c ), they estimated the electronic specific heat coefficient (γ), lower critical field (H c1 ), and Ginzburg-Landau parameter (κ) at 1.2 K 27 . Several carbides and nitrides with isotypic H-phases and phases with the filled and ordered -Mn structure were tested for superconductivity by L.E.…”

Section: Introductionmentioning

confidence: 99%

Structure and physical properties of the noncentrosymmetric superconductorMo3Al2C

et al. 2010

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We have synthesized polycrystalline samples of the noncentrosymmetric superconductor Mo 3 Al 2 C by arc and RF melting, measured its transport, magnetic and thermodynamic properties, and computed its band structure.Experimental results indicate a bulk superconducting transition at T c ~ 9.2 K, while the density of states at the Fermi surface is found to be dominated by Mo d-orbitals. Using the measured values for the lower critical field H c1 , upper critical field H c2 , and the specific heat C, we estimated the thermodynamic critical field H c (0), coherence length ξ(0), penetration depth λ(0), and the Ginzburg-Landau parameter κ(0). The specific heat jump at T c , ΔC/γT c = 2.14, suggests that Mo 3 Al 2 C is moderately-to-strongly coupled, consistent with the fast opening of the gap, as evidenced by the rapid release of entropy below T c from our electronic specific heat measurements. Above 2K the electronic specific heat exhibits the power law behavior, suggesting that synthesis of single crystals and measurements at lower temperature are needed to establish whether the gap is anisotropic. The estimated value of the upper critical field H c2 (0) is close to the calculated Pauli limit, therefore further studies are needed to determine whether the absence of an inversion center results in a significant admixture of the triplet component of the order parameter.

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High-Field Superconductivity of Carbides

Cited by 42 publications

References 12 publications

Density functional theory study of phase stability, vibrational, and electronic properties of Mo3Al2C

Density functional theory study of phase stability, vibrational, and electronic properties of Mo3Al2C

Successive superconducting transitions and Anderson localization effect inTa2S2C

Structure and physical properties of the noncentrosymmetric superconductorMo3Al2C

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