325ues of x,y,z chosen for minimum magnetic anisotropy and easy magnetization axis rotation near room temperature. As holmium replaces terbium and dysprosium in these compounds, this minimum anisotropy decreases until at a value of 2~0 . 5 8 both K, and K,=zero.' An important objective of this work is to determine how the width of the hysteresis loop depends upon holmium concentration and then compare this dependence with the decrease in magnetostriction as z is increased. Table I shows the fractional reduction in the width of the hysteresis curve, AHh/Hh, with 15% holmium substituted for Tb and Dy. (The reduction in AHh/Hh for a drive field of 72 kA/m is given for a wide range of compressive stresses, U ) . Clearly for all U, the hysteresis is reduced substantially, whereas only a small fraction reduction in magnetostriction ( AXIX) occurs using the same drive field. As z is increased, both the hysteresis and magnetosuiction are still further reduced.