Magnetic Order In Gdbipt Studied By X-Ray Resonant Magnetic Scattering

Rare-earth (R) half-Heusler compounds RBiPt exhibit a wide spectrum of interesting ground states. We have employed x-ray resonant magnetic scattering to elucidate the microscopic details of the magnetic structure in GdBiPt below T(N) = 8.5 K. Experiments at the Gd L(2) absorption edge show that the Gd moments order in an antiferromagnetic stacking along the cubic diagonal [111] direction, satisfying one of the requirements for an antiferromagnetic topological insulator as proposed previously, where both time-reversal symmetry and lattice translational symmetry are broken, but their product is conserved.