A nuclear magnetic resonance investigation of the ferromagnetic phase of CePdSb as a function of temperature and pressure

The ferromagnetic state of CePdSb below 17 K has been confirmed by zero-field Sb NMR. The effective field (B_eff) at the Sb nucleus at low temperature is +2.78 T and the quadrupole interaction (ν_q) is 3.8 (2.3) MHz for ¹²¹Sb (¹²³Sb). The NMR spectra do not reflect reported magnetic behaviour at 6 K. The transition at this temperature is therefore thought to be due to a second phase. The value of ∂ In B_eff/∂P is +6.3 Mbar^-1. which is similar to that of ∂ In T_C/∂P. +14 Mbar^-1. The value of ∂ In ν_q/∂P is -28 Mbar^-1, which is estimated to be ≈ -28 times the value expected for an Isotropic elastic solid. The elastic properties of CePdSb are therefore predicted to be extremely anisotropic. The temperature dependence of B_eff was measured from 1.4-15 K but measurements are required to lower temperatures before it can be decided whether a 4.5 K gap exists in the spin-wave spectrum, as postulated from heat capacity measurements.