Local electromagnetic properties of magnetic pnictides: A comparative study probed by NMR measurement

Abstract

75As and 31P 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 75As quadrupolar coupling constant, ${\nu }_Q$ increases continuously with the decrease of temperature and is found to vary linearly with the intrinsic spin susceptibility, Kiso. This indicates a possibility of the presence of a coupling between charge density and spin density fluctuations. Further, 31P NMR Knight shift and spin lattice relaxation rate (1/T1) in the paramagnetic state of NdCoPO indicate that the differences between LaCoPO and NdCoPO with SmCoPO are due to the decrement of inter layer separation and not due to the moments of 4f electrons. Nuclear spin lattice relaxation time (T1) in NdCoPO shows weak anisotropy at 300 K. Using self consistent renormalization (SCR)theory of itinerant ferromagnet, 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 ($T_0$, $T_A$, ${\bar{F}}_1$) are evaluated. The similarities and dissimilarities of the NMR results in As and P based systems, with different rare earths have also been discussed.

18 pages,13 figures, accepted for publication in J. Phys. Condens. Matter

References in corpus (11)

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• Superconductivity in Co-doped LaFeAsO
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• ${}^{75}$As NQR and NMR studies of superconductivity and electron correlations in iron arsenide Li${}_x$FeAs
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• Microscopic study of the effect of impurities on the first order spin density wave transition in BaFe${}_2$As${}_2$
• 75As NMR-NQR study in superconducting LiFeAs
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Cited by in corpus (4)

• Emergence of Orbital Nematicity in the Tetragonal Phase of BaFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$
• Antiferromagnetic spin correlations and pseudogap-like behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity
• Common effect of chemical and external pressures on the magnetic properties of $R$CoPO ($R$ = La, Pr, Nd, Sm). II
• Effect of external pressure on the magnetic properties of $R$CoAsO ($R$ = La, Pr, Sm): a $\mu$SR study