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 remains a puzzle.Here we report the 1H NMR measurem...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 remains a puzzle.Here we report the 1H 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 ^(1)T_(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 ^(1)T_(1)^(-1)∝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.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.51872328,11674392,11774401,and A0402/11927809)the National Key R&D Program of China(Grant Nos.2016YFA0300504 and 2016YFA0300401)+2 种基金China Postdoctoral Science Foundation(Grant No.2020M680797)the Fundamental Research Funds for the Central Universitiesthe Research Funds of Renmin University of China(Grant Nos.18XNLG24,20XNLG19,and 21XNLG18)。
文摘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 remains a puzzle.Here we report the 1H 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 ^(1)T_(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 ^(1)T_(1)^(-1)∝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.
