Sb-NMR/NQR studies of heavy fermion system YbRhSb

We report a study of ¹²¹Sb nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) in a Yb-based heavy fermion system YbRhSb using a single crystal. Sharp ¹²¹Sb-NMR lines were observed for each crystal axis for B‖a,b,c. From comparison with observed Sb-NMR spectra and numerical simulations, electric field gradient (EFG) parameters and Knight shift parameters are obtained at 10 K. The obtained quadrupole frequency, asymmetry parameter, isotropic Knight shift and anisotropic principal values of Knight shift tensors are ν_Q = 18.8 MHz, $\eta =0.2,\text{/hspace{0.17em}}{K}_{iso}\approx 0.6\%$, and $(K_{\text{ax}}^x,K_{\text{ax}}^y,K_{\text{ax}}^z)\approx (-3.5,4.1,-0.6)\%$, respectively. We also succeeded in observing ¹²¹Sb-NQR signals at around 19.5 and 37 MHz, which are reproduced by the nuclear quadrupole Hamiltonian with ν_Q = 18.8 MHz and η = 0.2. We mention the relation between the anisotropy of the Knight shift and magnetic susceptibility. Our NMR/NQR results suggest that the weak ferromagnetism in YbRhSb is ascribed to a canted antiferromagnetic state. (paper)