Xie Tao, Huo Mengwu, Ni Xiaosheng, Shen Feiran, Huang Xing, Sun Hualei, Walker Helen C, Adroja Devashibhai, Yu Dehong, Shen Bing, He Lunhua, Cao Kun, Wang Meng
Center for Neutron Science and Technology, Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, School of Physics, Sun Yat-sen University, Guangzhou 510275, China.
Spallation Neutron Source Science Center, Dongguan 523803, China.
Sci Bull (Beijing). 2024 Oct 30;69(20):3221-3227. doi: 10.1016/j.scib.2024.07.030. Epub 2024 Jul 19.
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 LaNiO 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 LaNiO 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 LaNiO.
经过几十年对高温超导的研究，尚未有关于其机制的确凿理论；然而，自旋涨落被广泛认为在形成超导库珀对中起着关键作用。近期在高压下双层镍酸盐LaNiO中发现近80K的高温超导性，为阐明高温超导的起源提供了一个新平台。我们在常压下对LaNiO的多晶样品进行了弹性和非弹性中子散射研究。在低至10K的温度下未发现磁有序。中子衍射测量中未出现长程磁有序可能归因于磁矩较小。然而，我们在约45meV的非弹性散射光谱中观察到一个微弱的平带自旋涨落信号。观察到的自旋激发可解释为条纹型反铁磁序的强层间和弱层内磁耦合的结果。我们的结果提供了关于自旋动力学的关键信息，因此对于理解LaNiO中的超导性很重要。
