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 (v(q)) is 3.8 (2.3) MHz for Sb-121 (Sb-123). The NMR spectra do nor 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 partial derivative ln B-eff/partial derivative P is +6.3 Mbar(-1), which is similar to that of partial derivative ln T-c/partial derivative P, +14 Mbar(-1). The value of partial derivative ln v(q)/partial derivative P is -28 Mbar(-1), which is estimated to be approximate to -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.