Magnetic hyperfine field in antiferromagnetic RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er) studied by perturbed angular correlation spectroscopy using 111Cd

The magnetic and electric hyperfine interactions of the nuclear probe Cd-111 in the hexagonal antiferromagnetic rare earth-gallium RGa2 (R = Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er) intermetallic compounds have been investigated by perturbed angular correlation (PAC) spectroscopy as a function of temperature. With the exception of R = Nd and Ho, the magnetic hyperfine field B-hf is roughly proportional to the spin projection (g - 1)(J) of the R constituent. However, in the group of the light rare earths, the variation of B-hf with (g - 1)(J) is much weaker than that for the heavy R constituents, in contrast to the trend reported for all rare earth intermetallics investigated up to now as well as to the trend of the magnetic ordering temperatures of RGa2. The orientation of the 4f spins relative to the c axis of RGa2 deduced from the angle between B-hf and the symmetry axis of the electric field gradient was found to be temperature independent and in agreement with the results of previous magnetization measurements. Except for SmGa2 where the hyperfine field shows an abrupt decrease near T-N, the temperature dependence of B-hf(T) is consistent with second order phase transitions. The magnetic ordering temperatures deduced from B-hf(T) agree with magnetization and neutron diffraction results. (C) 2013 American Institute of Physics.