Alloying effects of Y on in superconducting (La1−xY x)NiC2

Liao, Teng-Biao; Sung, H.H.; Syu, K.J.; Lee, W.H.

doi:10.1016/j.ssc.2008.12.043

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…13,14 Magnetism can be sometimes stabilized by doping but this does not occur in LaNiC 2 when doped with Y, Th, or Cu. [15][16][17] On the other hand, unconventional responses have been reported for LaNiC 2 in low-temperature specific heat 8 and magnetic penetration-depth 9 studies, and supported by evidence of time reversal symmetry (TRS) breaking. 10 However, there is no consensus about these results in the superconducting phase.…”

Section: Introductionmentioning

confidence: 92%

Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystal LaNiC2

Landaeta¹,

Subero²,

Machado³

et al. 2017

Phys. Rev. B

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Superconductivity in noncentrosymmetric LaNiC 2 is expected to be induced by electron-phonon interactions due to its lack of magnetic instabilities. The non-Bardeen-Cooper-Schrieffer (BCS) behaviors found in this material call into question the long-standing idea that relates unconventional superconductivity with magnetic interactions. Here we report magnetic penetration-depth measurements in a high-purity single crystal of LaNiC 2 at pressures up to 2.5 GPa and temperatures down to 0.04 K. At ambient pressure and below 0.5T c the penetration depth goes as T 4 for the in-plane and T 2 for the out-of-plane component, firmly implying the existence of point nodes in the energy gap and the unconventional character of this superconductor. The present study also provides first evidence of magnetism in LaNiC 2 by unraveling a pressure-induced antiferromagnetic phase inside the superconducting state at temperatures below 0.5 K, with a quantum critical point around ambient pressure. The results presented here maintain a solid base for the notion that unconventional superconductivity only arises near magnetic order or fluctuations. 1 arXiv:1806.03818v1 [cond-mat.supr-con]

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Section: Introductionmentioning

confidence: 92%

Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystal LaNiC2

Landaeta¹,

Subero²,

Machado³

et al. 2017

Phys. Rev. B

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“…13,14 At the time, however, the lack of inversion symmetry was largely overlooked. In contrast, very recently there has been a surge of experimental 11,15,16 and theoretical 11,[17][18][19] work on this system. Some of this has been motivated by the results in Ref.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to this dramatic dependences of T c on Cu, Y, and Th doping have been identified. 15,16,20,21 Two broad and mutually exclusive scenarios have been proposed to describe the breaking of TRS in the superconducting state of LaNiC 2 . 11,19 In the first scenario, which is based on group-theoretical considerations, 11 the superconducting order parameter is intrinsically unconventional: a nonunitary triplet pairing state.…”

Section: Introductionmentioning

confidence: 99%

Relativistic analysis of the pairing symmetry of the noncentrosymmetric superconductorLaNiC2

et al. 2010

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We present a relativistic symmetry analysis of the allowed pairing states in the noncentroymmetric superconductor LaNiC 2 . The case of zero spin-orbit coupling ͑SOC͒ is discussed first and then the evolution of the symmetry-allowed superconducting instabilities as SOC is adiabatically turned on is described. In addition to mixing singlet with triplet pairing, SOC splits some triplet pairing states with degenerate order-parameter spaces into nondegenerate pairing states with different critical temperatures. We address the breaking of time-reversal symmetry detected in recent muon spin-relaxation experiments and show that it is only compatible with such nonunitary triplet pairing states. In particular, an alternative scenario featuring conventional singlet pairing with a small admixture of triplet pairing is shown to be incompatible with the experimental data.

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“…FIG.12. Upper panel: The computed specific heat of the superconducting state as a function of the reduced temperature for p = 0 GPa, compared with the experimental data: Lee et al[1], Chen et al[15], Hirose et al[18], Pecharsky et al[20] and Liao et al[60]. Lower panel: reduced specific heat of the superconducting state (lines with symbols) as a function of temperature and pressure.…”

mentioning

confidence: 99%

Pressure effects on the unconventional superconductivity of noncentrosymmetric LaNiC2

et al. 2016

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The unconventional superconductivity in the noncentrosymmetric LaNiC2, and its evolution with pressure, is analyzed basing on the ab initio computations and the full Eliashberg formalism. First principles calculations of the electronic structure, phonons and the electron-phonon coupling are reported in the pressure range 0-15 GPa. The thermodynamic properties of the superconducting state were determined numerically solving the Eliashberg equations. We found that already at p = 0 GPa, the superconducting parameters deviate from the BCS-type, and a large value of the Coulomb pseudopotential µ ⋆ = 0.22 is required to get the critical temperature Tc = 2.8 K consistent with experiment. If such µ ⋆ is used, the Eliashberg formalism reproduces also the experimentally observed values of the superconducting order parameter, the electronic specific heat jump at the critical temperature, and the change of the London penetration depth with temperature. This shows, that deviation of the above-mentioned parameters from the BCS predictions do not prejudge on the triplet or multiple gap nature of the superconductivity in this compound. Under the external pressure, calculations predict continuous increase of the electron-phonon coupling constant in the whole pressure range 0-15 GPa, consistent with the experimentally observed increase in Tc for the pressure range 0-4 GPa, but inconsistent with the drop of Tc above 4 GPa and the disappearance of the superconductivity above 7 GPa, reported experimentally. The disappearance of superconductivity may be accounted for by increasing the µ ⋆ to 0.36 at 7 GPa, which supports the hypothesis of the formation of a new high-pressure electronic phase, which competes with the superconductivity.

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Alloying effects of Y on in superconducting (La1−xY x)NiC2

Cited by 14 publications

References 13 publications

Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystal LaNiC2

Unconventional superconductivity and an ambient-pressure magnetic quantum critical point in single-crystal LaNiC2

Relativistic analysis of the pairing symmetry of the noncentrosymmetric superconductorLaNiC2

Pressure effects on the unconventional superconductivity of noncentrosymmetric LaNiC2

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