Microscopic Observation of Heavy Quasiparticle Formation in the Intermediate Valence Compound EuNi${}_2$P${}_2$: ${}^{31}$P NMR Study

Abstract

We report ${}^{31}$P NMR measurements under various magnetic fields up to 7 T for the intermediate valence compound EuNi${}_2$P${}_2$, which shows heavy electronic states at low temperatures. In the high-temperature region above 40 K, the Knight shift followed the Curie--Weiss law reflecting localized $4f$ states. In addition, the behavior corresponding to the temperature variation of the average valence of Eu was observed in the nuclear spin-lattice relaxation rate $1/T_1$. With the occurrence of the Kondo effect, $1/T_1$ was clearly reduced below 40 K, and the Knight shift becomes almost constant at low temperatures. From these results, the formation of heavy quasiparticles by the hybridization of Eu $4f$ electrons and conduction electrons was clarified from microscopic viewpoints. Furthermore, a characteristic spin fluctuation was observed at low temperatures, which would be associated with valence fluctuations caused by the intermediate valence state of EuNi${}_2$P${}_2$.

arXiv comment7 pages, 5 figures

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Cited by in corpus (3)

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• Gapped Spin Excitation in Magnetic Ordered State on Yb-Based Zigzag Chain Compound YbAgSe2