摘要
After several decades of studies of high-temperature superconductivity,there is no compelling theory for the mechanism yet;however,the spin fluctuations have been widely believed to play a crucial role in forming the superconducting Cooper pairs.The recent discovery of high-temperature superconductivity near 80 K in the bilayer nickelate La_(3)Ni_(2)O_(7)under pressure provides a new platform to elucidate the origins of high-temperature superconductivity.We perform elastic and inelastic neutron scattering studies on a polycrystalline sample of La_(3)Ni_(2)O_(7-δ)at ambient pressure.No magnetic order can be identified down to 10 K.The absence of long-range magnetic order in neutron diffraction measurements may be ascribed to the smallness of the magnetic moment.However,we observe a weak flat spin-fluctuation signal in the inelastic scattering spectra at~45 meV.The observed spin excitations could be interpreted as a result of strong interlayer and weak intralayer magnetic couplings for stripe-type antiferromagnetic orders.Our results provide crucial information on the spin dynamics and are thus important for understanding the superconductivity in La_(3)Ni_(2)O_(7).
基金
supported by the National Key Research and Development Program of China(2023YFA1406500,2023YFA1406000)
the National Natural Science Foundation of China(12304187,12174454,U21301001)
the Guangdong Basic and Applied Basic Research Funds(2024B1515020040,2024A1515030030,2022A1515011618)
Guangzhou Basic and Applied Basic Research Funds(202201011123,2024A04J4024,2024A04J6417)
Shenzhen Science and Technology Program(RCYX20231211090245050)
Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(2022B1212010008)
the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(23qnpy57)
the open research fund of Songshan Lake Materials Laboratory(2023SLABFN30)。
