Determination of the crystal field parameters in SmFe11Ti

The magnetization of SmFe11Ti single crystals has been measured along the principal crystallographic directions in steady (14 T) and pulsed (43 T) magnetic fields. The fourfold symmetry axis [001] is an easy magnetization direction. The magnetization curves measured in directions perpendicular to [001] are remarkable in two ways: (i) They do not depend on orientation of H within the basal plane; (ii) at low temperature they are S shaped, with an inflection point at about 0.6 times saturation magnetization. These two facts enable us to conclude that three out of five crystal field parameters of SmFe11Ti are negligibly small; only A02 and A06 are essentially nonzero. A comparison with an isomorphous compound DyFe11Ti reveals a dramatic disparity of their crystal fields, especially as regards A44 , nearly zero in SmFe11Ti but outstandingly large in DyFe11Ti.