Spin fluctuations of the uranium 5f-electrons in UN according to 14N-NMR data

The results of the study of the paramagnetic region of uranium mononitride by the method of nuclear magnetic resonance (NMR)of ¹⁴N nuclei are presented.The ¹⁴N NMR spectra, the Knight shifts K, the spin-lattice relaxation times T ₁ have been obtained within the temperature range T = 60 – 375 K and at magnetic fields 92.8 kOe and 117.5 kOe. The temperature dependence of the Knight shift of the ¹⁴N line is proportional to the spin susceptibility χ of 5f-electrons of uranium. The ratio of the experimentally determined value T T ₁ K ² to the theoretically calculated value of the Korringa contribution is 21.5 (at T = 295 K), which is significantly more than for common metals. This suggests that nuclear relaxation is based on the same mechanism as the Knight shift, namely, the indirect connection between the ¹⁴N nuclei and the localized magnetic moments of uranium through conduction electrons. The experimental results on the T-dependence of the spin-lattice relaxation rate of ¹⁴N also do not contradict the assumption that uranium mononitride is a concentrated Kondo system.