Long range spin ferromagnetic order with zero magnetization in (111) Sm1-xGdxAl2 films

摘要

Bulk Sm1-xGdxAl2 (0.01 < x < 0.035) compound exhibits an exciting magnetic property: its magnetization drops to zero at a compensation temperature T-comp while it maintains a long range ferromagnetic order. We achieved recently the first epitaxial growth of (111) Sm1-xGdxAl2 films by molecular beam epitaxy. Macroscopic magnetization measurements confirmed the existence of a magnetic compensated state, occurring at a temperature that depends on the concentration of Gd. Specific features observed in the Sm1-xGdxAl2 films are a strong [111] perpendicular anisotropy and a very large coercivity. X-ray magnetic circular dichroism at Sm and Gd L-2,(3) edges allows us to directly evidence the existence of a long range magnetic polarization of the Sm and Gd sublattices at T-comp, and a parallel coupling between the total magnetic moment of Sm3+ and Gd3+. Moreover, it is possible to tailor the magnetic behavior at T-comp by changing the thermo-magnetic treatment.