Preferred Spin Excitations in the Bilayer Iron-Based Superconductor $$CaK(Fe_{0.96}Ni_{0.04})_4As_4$$ with Spin-Vortex Crystal Order
- Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS); University of Chinese Academy of Sciences, Beijing (China)
- Univ. Paris-Saclay, Gif-sur-Yvette (France). Laboratoire Léon Brillouin; Alternative Energies and Atomic Energy Commission (CEA), Saclay (France)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Peking Univ., Beijing (China). International Center for Quantum Materials
- Univ. Grenoble Alpes, Grenoble (France)
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia). Australian Centre for Neutron Scattering
- Raja Ramanna Centre for Advanced Technology, Indore (India); Homi Bhabha National Inst., Mumbai (India)
- Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS); University of Chinese Academy of Sciences, Beijing (China); Songshan Lake Materials Lab., Dongguan (China)
- Peking Univ., Beijing (China). International Center for Quantum Materials; Collaborative Innovation Center of Quantum Matter, Beijing (China)
- Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Physics. Beijing National Lab. for Condensed Matter Physics (BNLCP-CAS); Songshan Lake Materials Lab., Dongguan (China)
Spin-orbit coupling (SOC) is a key to understand the magnetically driven superconductivity in iron-based superconductors, where both local and itinerant electrons are present and the orbital angular momentum is not completely quenched. Here, we report a neutron scattering study on the bilayer compound CaK(Fe0.96Ni0.04)4As4 with superconductivity coexisting with a noncollinear spin-vortex crystal magnetic order that preserves the tetragonal symmetry of the Fe-Fe plane. In the superconducting state, two spin resonance modes with odd and even L symmetries due to the bilayer coupling are found similar to the undoped compound CaKFe4As4 but at lower energies. Polarization analysis reveals that the odd mode is c-axis polarized, and the low-energy spin anisotropy can persist to the paramagnetic phase at high temperature, which closely resembles other systems with in-plane collinear and c-axis biaxial magnetic orders. Overall, these results provide the missing piece of the puzzle on the SOC effect in iron-pnictide superconductors, and also establish a common picture of c-axis preferred magnetic excitations below Tc regardless of the details of magnetic pattern or lattice symmetry.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division; National Key Research and Development Program of China; National Natural Science Foundation of China (NSFC)
- Grant/Contract Number:
- AC05-00OR22725; 2020YFA0406003; 2018YFA0704200; 2018YFA0305602; 2017YFA0302900; 11822411; 11888101; 11874069; 11961160699; 11674406
- OSTI ID:
- 1863280
- Journal Information:
- Physical Review Letters, Vol. 128, Issue 13; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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