Thermal expansion of CePdSb near the ferromagnetic transition

The thermal expansion of CePdSb has been measured between 1.6 and 30 K in magnetic fields of up to 8 T. The magnetic contribution to the linear thermal-expansion coefficient of polycrystalline CePdSb ((Formula presented)) in zero magnetic field has a maximum value near 10 K and becomes small by 20 K. There is no peak in (Formula presented) at the Curie point, (Formula presented)=17 K. This anomalous behavior is in agreement with earlier heat-capacity measurements. The maximum value of (Formula presented) decreases in a magnetic field and moves to a higher temperature. The thermal expansion of a single crystal of CePdSb was found to be highly anisotropic. In the magnetically hard c direction the thermal-expansion coefficient ((Formula presented)) has a maximum value near 10 K some three times larger than that of the peak in (Formula presented). The value of (Formula presented) is negative above (Formula presented) and then shows the beginnings of a normal critical response near (Formula presented) before being submerged in the broad 10 K peak. The values of (Formula presented) ((Formula presented)) are small in magnitude and negative (positive) below 14 K in zero field but both become positive in a field of 8 T. The strong secondary peak in the ac susceptibility of CePdSb reported earlier, some 11 K below (Formula presented), was observed in samples prepared by arc melting but not in those produced in sealed crucibles and is therefore probably due to material with a deficiency of Sb.