Neutron spin resonance in a quasi-two-dimensional iron-based superconductor
| Autor: | Hong, Wenshan, Song, Linxing, Liu, Bo, Li, Zezong, Zeng, Zhenyuan, Li, Yang, Wu, Dingsong, Sui, Qiangtao, Xie, Tao, Danilkin, Sergey, Ghosh, Haranath, Ghosh, Abyay, Hu, Jiangping, Zhao, Lin, Zhou, Xingjiang, Qiu, Xianggang, Li, Shiliang, Luo, Huiqian |
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| Rok vydání: | 2020 |
| Předmět: | |
| Zdroj: | Phys. Rev. Lett. 125, 117002 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevLett.125.117002 |
| Popis: | Magnetically mediated Cooper pairing is generally regarded as a key to establish the unified mechanism of unconventional superconductivity. One crucial evidence is the neutron spin resonance arising in the superconducting state, which is commonly interpreted as a spin-exciton from collective particle-hole excitations confined below the superconducting pair-breaking gap ($2\Delta$). Here, on the basis of inelastic neutron scattering measurements on a quasi-two-dimensional iron-based superconductor KCa$_2$Fe$_4$As$_4$F$_2$, we have discovered a two-dimensional spin resonant mode with downward dispersions, a behavior closely resembling the low branch of the hour-glass-type spin resonance in cuprates. The resonant intensity is predominant by two broad incommensurate peaks near $Q=$(0.5, 0.5) with a sharp energy peak at $E_R=16$ meV. The overall energy dispersion of the mode exceeds the measured maximum total gap $\Delta_{\rm tot}=|\Delta_k|+|\Delta_{k+Q}|$. These experimental results deeply challenge the conventional understanding of the resonance modes as magnetic excitons regardless of underlining pairing symmetry schemes, and it also points out that when the iron-based superconductivity becomes very quasi-two-dimensional, the electronic behaviors are similar to those in cuprates. Comment: 16 pages, 14 figures, including supplementary materials |
| Databáze: | arXiv |
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