Magnetic structure of Gd, GdH2 and NdH2 single crystal films

Single crystal films of Gd and Nd were grown by MBE techniques using the LaMBE facility in Oxford. The thickness of the layers was 5000 A and the mosaic spread about 0.2-0.3 deg. Some of the layers were hydrogenated by KTH in Stockholm to obtain the dihydride. The magnetic structures were determined using the TAS1 triple axis spectrometer at the Risoe National Laboratory in Denmark. The magnetic structure of the Gd film was a ferromagnet, similar to that of bulk Gd. In detail, however, there were differences and the spin direction differed from that of the bulk material while the phase with the moments aligned along the c-axis was absent in the film. The magnetic structure of GdH2 was antiferromagnetic with a wavevector of (1/2 1/2 1/2) and a transition temperature of 22±0.5 K, much lower than that of bulk Gd, 290 K. In contrast, the magnetic structure of NdH2 is incommensurate with a wavevector of (0.532 0.532 1.532) and a magnetic ordering temperature of 34±1 K. (author)