ECMP Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata, India.
J Phys Condens Matter. 2013 May 15;25(19):196002. doi: 10.1088/0953-8984/25/19/196002. Epub 2013 Apr 19.
(75)As and (31)P NMR studies are performed in PrCoAsO and NdCoPO respectively. The Knight shift data in PrCoAsO indicate the presence of an antiferromagnetic interaction between the 4f moments along the c axis in the ferromagnetic state of Co 3d moments. We propose a possible spin structure in this system. The (75)As quadrupolar coupling constant, νQ, increases continuously with decrease of temperature and is found to vary linearly with the intrinsic spin susceptibility, K(iso). This indicates the possibility of the presence of a coupling between charge density and spin density fluctuations. Further, the (31)P NMR Knight shift and spin-lattice relaxation rate (1/T1) in the paramagnetic state of NdCoPO indicate that the differences of LaCoPO and NdCoPO from SmCoPO are due to the decrement of the interlayer separation and not due to the moments of the 4f electrons. The nuclear spin-lattice relaxation time (T1) in NdCoPO shows weak anisotropy at 300 K. Using the self-consistent renormalization (SCR) theory of itinerant ferromagnets, it is shown that in the ab plane, the spin fluctuations are three-dimensional ferromagnetic in nature. From SCR theory the important spin-fluctuation parameters (T0, TA, F¯1) are evaluated. The similarities and dissimilarities of the NMR results in As and P based systems with different rare earths are also discussed.
（75）As 和（31）P NMR 研究分别在 PrCoAsO 和 NdCoPO 中进行。PrCoAsO 中的 Knight 位移数据表明，在 Co 3d 磁矩的铁磁态中，4f 磁矩沿 c 轴存在反铁磁相互作用。我们提出了该体系中可能的自旋结构。（75）As 四极耦合常数 νQ 随温度的降低而连续增加，并发现与本征自旋磁化率 K(iso) 呈线性关系。这表明电荷密度和自旋密度涨落之间可能存在耦合。此外，NdCoPO 中（31）P NMR Knight 位移和自旋晶格弛豫率（1/T1）在顺磁态中表明，LaCoPO 和 NdCoPO 与 SmCoPO 的区别在于层间距离的减小，而不是 4f 电子的磁矩。NdCoPO 中的核自旋晶格弛豫时间（T1）在 300 K 时表现出较弱的各向异性。利用巡游铁磁体的自洽重整化（SCR）理论，表明在 ab 平面内，自旋涨落本质上是三维铁磁的。从 SCR 理论中评估了重要的自旋涨落参数（T0、TA、F¯1）。还讨论了基于 As 和 P 的不同稀土元素的 NMR 结果的相似性和差异性。
