NMR Evidence of Antiferromagnetic Spin Fluctuations in Nd0.85Sr0.15NiO2
NMR Evidence of Antiferromagnetic Spin Fluctuations in Nd0.85Sr0.15NiO2
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Nd0.85Sr0.15NiO2 中反铁磁自旋涨落的 NMR 证据
DOI：
10.1088/0256-307x/38/6/067401
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发表时间：
2021-06-01
影响因子：
3.5
通讯作者：
Yu, Weiqiang
中科院分区：
文献类型：
--
作者：
Cui, Yi;Li, Cong;Yu, Weiqiang
尽管最近在Nd_（1-x）Sr（x）NiO_2薄膜中发现了超导电性，但在其块体材料中缺乏超导电性和反铁磁性仍然是一个谜。在这里，我们报告的H-1 NMR测量粉末Nd 0.85 Sr 0.15 NiO 2样品利用氢退火后的富集质子浓度。我们发现了一个很大的光谱半峰全宽，它随着温度T的降低而不断增加，并在低温下表现出一个上翘的行为。自旋-晶格弛豫速率T-1（1）-1随温度的降低而增强，在40 K左右出现一个宽峰，然后在较低温度下随T-1（1）-1呈自旋波状下降，T-1（1）-1与T-2成正比。这些结果证明了一个短程玻璃反铁磁有序磁矩低于40 K和占主导地位的反铁磁波动延伸到更高的温度。我们的研究结果揭示了强烈的电子相关性在体Nd0.85Sr0.15NiO2，并阐明了镍酸盐薄膜中观察到的超导电性机制。
Despite the recent discovery of superconductivity in Nd1-x Sr (x) NiO2 thin films, the absence of superconductivity and antiferromagnetism in their bulk materials remains a puzzle. Here we report the H-1 NMR measurements on powdered Nd0.85Sr0.15NiO2 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 T and exhibits an upturn behavior at low temperatures. The spin-lattice relaxation rate T-1(1)-1 is strongly enhanced when lowering the temperature, developing a broad peak at about 40 K, then decreases following a spin-wave-like behavior T-1(1)-1 proportional to 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 Nd0.85Sr0.15NiO2, and shed light on the mechanism of superconductivity observed in films of nickelates.