We have investigated the transition between the easy-axis and easy-plane type of magnetocrystalline anisotropy in the TbNi(Al,In) series. These compounds crystallize in the hexagonal ZrNiAl-type structure and order magnetically at low temperatures.
TbNiAl is an antiferromagnet below 47 K with the moments aligned along the c-axis, whereas TbNiIn orders magnetically below 70 K with moments perpendicular to the c-axis. The presented study is based mainly on the low temperature x-ray powder diffraction performed in presence of external magnetic field.
We have revealed that the transition between both types of anisotropy occurs in compounds with In concentration around 30%.