Magnetic anisotropy and spontaneous magnetostriction of RCuAl (R=Gd, Dy, Ho)

We have studied the magnetic anisotropy and the spontaneous magnetostriction of the hexagonal RCuAl (R = Gd, Dy and Ho) compounds by means of X-ray diffraction. A uniaxial magnetic anisotropy in DyCuAl and GdCuAl and a basal-plane type of magnetic anisotropy in HoCuAl have been found. The temperature development of lattice parameters revealed a considerable linear spontaneous magnetostriction both in the basal plane and along the c-axis. The mutual cancellation of these linear effects of opposite sign yields a tiny volume spontaneous magnetostriction.