论文标题
ND $ _ {0.85} $ sr $ _ {0.15} $ nio $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $ _ 2 $
NMR Evidence of Antiferromagnetic Spin Fluctuations in Nd$_{0.85}$Sr$_{0.15}$NiO$_2$
论文作者
论文摘要
尽管最近发现了ND $ _ {1-x} $ sr $ _ {x} $ nio $ _2 $薄膜，但其散装材料中缺乏超导性和反铁磁性仍然是一个难题。在这里，我们报告了$^{1} $ h NMR测量粉末，$ _ {0.85} $ sr $ _ {0.15} $ nio $ _2 $样品通过利用氢后的富集质子浓度。我们发现频谱一半的最大宽度很大，随着温度的降低，这会不断增加，并在低温下表现出上涨行为。降低温度时，自旋晶格放松率$ 1/^{1} t_1 $在降低温度时会大大增强，在大约40 K处发展一个宽峰，然后在类似自旋波的行为$ 1/^{1} t_1 {\ sim} t_1 {\ sim} t^2 $下降低。这些结果证明，低于40 K以下的磁矩和主要的抗铁磁波动的短距离玻璃抗铁磁有序延伸到更高的温度。我们的发现揭示了大量$ _ {0.85} $ sr $ _ {0.15} $ nio $ _2 $中的强电子相关性，并阐明了在镍胶片中观察到的超导性的机制。
Despite the recent discovery of superconductivity in Nd$_{1-x}$Sr$_{x}$NiO$_2$ thin films, the absence of superconductivity and antiferromagnetism in their bulk materials remain a puzzle. Here we report the $^{1}$H NMR measurements on powdered Nd$_{0.85}$Sr$_{0.15}$NiO$_2$ samples by taking advantage of the enriched proton concentration after hydrogen annealing. We find a large full width at half maximum of the spectrum, which keeps increasing with decreasing the temperature and exhibits an upturn behavior at low temperatures. The spin-lattice relaxation rate $1/^{1}T_1$ is strongly enhanced when lowering the temperature, developing a broad peak at about 40 K, then decreases following a spin-wave-like behavior $1/^{1}T_1{\sim}T^2$ at lower temperatures. These results evidence a short-range glassy antiferromagnetic ordering of magnetic moments below 40 K and dominant antiferromagnetic fluctuations extending to much higher temperatures. Our findings reveal the strong electron correlations in bulk Nd$_{0.85}$Sr$_{0.15}$NiO$_2$, and shed light on the mechanism of superconductivity observed in films of nickelates.
