Paramagnetic state of the kagome Kondo lattice compound YbVSn; A V nuclear magnetic resonance study

Park, S.*; Sakai, Hironori   ; Hosoi, Suguru*; Thomas, S. M.*; Kambe, Shinsaku*  ; Tokunaga, Yo  ; Dioguardi, A. P.*; Thompson, J. D.*; Ronning, F.*; Kimata, Motoi; Furukawa, Tetsuya*; Sasaki, Takahiko*; Bauer, E. D.*; Hirata, Michihiro*

YbVSn is a Kondo lattice compound with a layered structure composed of a triangular lattice of Yb ions and a vanadium-based kagome network, and it orders antiferromagnetically at K. We performed a V-NMR study of its paramagnetic state. The field-angular dependence of single-crystal NMR spectra allowed us to determine the principal axes of the electric field gradient tensor, the quadrupole frequency , and the asymmetry parameter at the V sites. Knight-shift and susceptibility analyses revealed anisotropic hyperfine couplings, while the spin-lattice relaxation rate showed enhanced low-energy spin fluctuations below ~K with strong in-plane anisotropy. A further field-tunable enhancement below ~K suggests proximity to the very-low-temperature antiferromagnetic instability.