Pressure-induced superconductivity in Sc to<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>74</mml:mn><mml:mspace width="0.3em" /><mml:mi>GPa</mml:mi></mml:mrow></mml:math>

Hamlin, J. J.; Schilling, J. S.

doi:10.1103/physrevb.76.012505

Cited by 29 publications

(35 citation statements)

References 27 publications

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“…3a, at 81 GPa a superconducting transition does appear where T c increases with pressure to a value as high as 19.6 K at 107 GPa, but then drops to a much lower temperature at 123 GPa. The magnitude of the superconducting transition (∼ 20-30 nV), which is consistent with 100% shielding, is much larger than that (∼ 3-4 nV) in the previous nearly hydrostatic experiments on Sc by Hamlin et al [23] to 74.2 GPa. This is due to the larger sample volume and larger demagnetization factor in the present nonhydrostatic experiments.…”

Section: Sc Metalmentioning

confidence: 62%

“…For this reason the superconducting transition of the sample can only be reliably detected if it occurs at a temperature T c 5.5 K. A relatively low noise level of a few tenths of a nanovolt is achieved by: (a) using the transformer preamplifier to ensure good impedance matching, (b) varying the temperature very slowly (100 mK/min) at low temperatures, (c) using a long time constant (> 3 s) on the lock-in amplifier, and (d) averaging over 2-3 measurements. Further experimental details of the high pressure and ac susceptibility techniques are published elsewhere [23,27,31].…”

Section: Methodsmentioning

confidence: 99%

“…As the relative increase in N d with pressure is particularly large for the "early" transition metals where N d is small, we focus our attention first on the four trivalent d-electron metals Sc, Y, La, and Lu, of which only La superconducts at ambient pressure. Previous high-pressure studies on Sc [23], Y [10], La [15], and Lu [24] were restricted to pressures of 74, 115, 50, and 28 GPa, respectively. Here we present new data which determine T c (P ) for Sc and Lu to the significantly higher pressures of 123 and 174 GPa, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

2008

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Whereas dhcp La superconducts at ambient pressure with T c ≃ 5 K, the other trivalent d-electron metals Sc, Y, and Lu only superconduct if high pressures are applied. Earlier measurements of the pressure dependence of T c for Sc and Lu metal are here extended to much higher pressures. Whereas T c for Lu increases monotonically with pressure to 12.4 K at 174 GPa (1.74 Mbar). T c for Sc reaches 19.6 K at 107 GPa, the 2nd highest value observed for any elemental superconductor. At higher pressures a phase transition occurs whereupon T c drops to 8.31 K at 111 GPa. The T c (P ) dependences for Sc and Lu are compared to those of Y and La. An interesting correlation is pointed out between the value of T c and the fractional free volume available to the conduction electrons outside the ion cores, a quantity which is directly related to the number of d electrons in the conduction band.

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Section: Sc Metalmentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

2008

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“…Both Sr and Ba are superconductors at high pressure and the critical temperature T C increases with pressure (10). The Sc-II phase was found to be superconducting (11) and recent observations show that T C also increases monotonically with pressure (12). Following through the arguments given above, one can expect Ca to undergo a similar transition to a complex phase at very high pressures.…”

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confidence: 93%

Prediction of incommensurate crystal structure in Ca at high pressure

Arapan

Mao

Ahuja

2008

Proc. Natl. Acad. Sci. U.S.A.

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Ca shows an interesting high-pressure phase transformation sequence, but, despite similar physical properties at high pressure and affinity in the electronic structure with its neighbors in the periodic table, no complex phase has been identified for Ca so far. We predict an incommensurate high-pressure phase of Ca from first principle calculations and describe a procedure of estimating incommensurate structure parameters by means of electronic structure calculations for periodic crystals. Thus, by using the ab initio technique for periodic structures, one can get not only reliable information about the electronic structure and structural parameters of an incommensurate phase, but also identify and predict such phases in new elements.ab initio calculations ͉ alkali metals T he continuous improvement of the high-pressure technique and the advances in the methods of characterization of materials under high pressure have opened new perspectives for materials physics community. The discovery of a series of phases for periodic table elements within the explored interval of pressures (1, 2) have stimulated an increased interest from both experimentalists and theoreticians to understand the unexpected behavior of simple elements under high pressure. Within the alkali and earth-alkaline metals, a series of complex structures at high pressure have been identified and, in particular, the complex phases of Ba-IV (3), Sr-V (4), Rb-IV (5), and K-III (6) have been determined as composite host-guest structures, which are incommensurate along the common axis of host and guest sub-lattices. The occurrence of such complex composite structures in a large number of elements and the robustness of these complex phases over a wide range of pressures and temperatures make the existence of composite incommensurate structures an intrinsic high-pressure phenomenon. Therefore, other elements may undergo similar high-pressure phase transitions. The nature of the transition to a composite structure is not completely understood yet, partly, because such an essential theoretical tool for describing the condensed matter as electronic structure calculations cannot be directly applied to study an incommensurate structure. However, one can perform first-principles calculations on commensurate analogues of an incommensurate phase and, indeed, such calculations can reproduce the phase transition sequence in close agreement with the experiment and provide reliable information about the electronic structure (7,8). Ab initio calculations of Ba-IV commensurate analogue (7) suggest that the transition from a closed, packed structure at low pressure to a more open, complex structure at high pressure might be because of the transfer of electrons from free-electron like s-bands to more directional d-bands. In the Ba-IV phase, the sd-hybridization occurs between the orbitals of two nonequivalent Ba atoms: guest atoms with a more d-like character and host atoms with a more s-like character. Therefore, from the electronic structure perspective, the composite s...

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“…T c increases with increasing pressure and exceeds 20 K at ~100 GPa [2], which is the highest T c in all elemental metals. Sc exhibits a superconducting transition above ~60 GPa, which approaches 20 K at 107 GPa [3,4]. At higher pressures, however, Sc undergoes a structural phase transition to a nonsuperconducting phase (Sc-III).…”

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confidence: 99%

Superconductivity in the Hexagonal Ternary Phosphide ScIrP

et al. 2016

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We report the discovery of a bulk superconducting transition at 3.4 K in the ternary phosphide, ScIrP, which crystallizes in a hexagonal ZrNiAl-type structure without spatial inversion symmetry. On the basis of heat capacity data in a zero magnetic field, ScIrP is suggested to be a weakly-coupled Bardeen-Cooper-Schrieffer superconductor. Alternatively, experimental results under magnetic fields indicate that this material is a type-II superconductor with an upper critical field H c2 at magnetic fields above 5 T at zero temperature. This moderately high H c2 does not violate the Pauli limit, but it does imply that there is a significant effect from the strong spin-orbit interaction of Ir 5d electrons in the noncentrosymmetric crystal structure. Electronic structure calculations show an interesting feature of ScIrP, where both the Sc 3d and Ir 5d orbitals contribute to the electronic density of states at the Fermi level.Elemental Ca and Sc show superconductivity with a relatively high transition temperature T c of ~20 K at high pressures. Ca is not a superconductor at ambient pressure but becomes superconducting above ~50 GPa [1]. T c increases with increasing pressure and exceeds 20 K at ~100 GPa [2], which is the highest T c in all elemental metals. Sc exhibits a superconducting transition above ~60 GPa, which approaches 20 K at 107 GPa [3,4]. At higher pressures, however, Sc undergoes a structural phase transition to a nonsuperconducting phase (Sc-III). If this transition did not occur, Sc would exhibit a T c higher than 20 K. In simple-metal superconductors such as Al, Sn, and Pb, T c decreases with increasing pressure due to a decrease of the electronic density of states (DOS). The pressure effects on T c in Ca and Sc, opposite to those in simple metals, have been discussed in terms of the pressure-induced s−d electron transfer where 4s electrons are dominant for electron conduction at ambient pressure and are transferred to the narrower 3d band by applying pressure [4,5]. The electrons occupying the 3d band play an important role in relatively high T c superconductivity.

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Pressure-induced superconductivity in Sc to74GPa

Cited by 29 publications

References 27 publications

Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

Comparison of the pressure dependences ofTcin the trivalentd-electron superconductors Sc, Y, La, and Lu up to megabar pressures

Prediction of incommensurate crystal structure in Ca at high pressure

Superconductivity in the Hexagonal Ternary Phosphide ScIrP

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