Two-Gap Superconductivity inLaNiGa2with Nonunitary Triplet Pairing and Even Parity Gap Symmetry
| Autor: | Frank Steglich, Tian Shang, Yuntian Chen, Michael Nicklas, Junxiang Zhang, Jorge Quintanilla, Z. F. Weng, James F. Annett, W. B. Jiang, Michael Smidman, G. M. Pang, Huiqiu Yuan, Lin Jiao |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Superconductivity Condensed matter physics London penetration depth General Physics and Astronomy 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Symmetry (physics) T-symmetry Condensed Matter::Superconductivity Pairing Quantum mechanics 0103 physical sciences 010306 general physics 0210 nano-technology Wave function Critical field Spin-½ |
| Zdroj: | Physical Review Letters. 117 |
| ISSN: | 1079-7114 0031-9007 |
| DOI: | 10.1103/physrevlett.117.027001 |
| Popis: | The nature of the pairing states of superconducting LaNiC_{2} and LaNiGa_{2} has to date remained a puzzling question. Broken time reversal symmetry has been observed in both compounds and a group theoretical analysis implies a nonunitary triplet pairing state. However, all the allowed nonunitary triplet states have nodal gap functions but most thermodynamic and NMR measurements indicate fully gapped superconductivity in LaNiC_{2}. Here we probe the gap symmetry of LaNiGa_{2} by measuring the London penetration depth, specific heat, and upper critical field. These measurements demonstrate two-gap nodeless superconductivity in LaNiGa_{2}, suggesting that this is a common feature of both compounds. These results allow us to propose a novel triplet superconducting state, where the pairing occurs between electrons of the same spin, but on different orbitals. In this case the superconducting wave function has a triplet spin component but isotropic even parity gap symmetry, yet the overall wave function remains antisymmetric under particle exchange. This model leads to a nodeless two-gap superconducting state which breaks time reversal symmetry, and therefore accounts well for the seemingly contradictory experimental results. |
| Databáze: | OpenAIRE |
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